Pyridazinone compounds as phosphodiesterase inhibitors and methods of treating disorders

ABSTRACT

The present invention provides a compound which has the effect of PDE inhibition, and which is useful as a medicament for preventing or treating schizophrenia or so on. 
     A compound of formula (I 0 ) 
     
       
         
         
             
             
         
       
         
         
           
             wherein 
             R 1  represents 
             a substituent, 
             R 2  represents 
             a hydrogen atom, or a substituent, 
             R 3  represents 
             a hydrogen atom, or a substituent, 
             Ring A represents 
             an aromatic ring which can be substituted, and 
             Ring B represents 
             a 5-membered heteroaromatic ring which can be substituted, 
             or a salt thereof.

PRIORITY INFORMATION

This application is a continuation of U.S. application Ser. No.14/517,313, issued as U.S. Pat. No. 9,550,756 on Jan. 24, 2017, which isa divisional application of U.S. application Ser. No. 12/656,605, issuedas U.S. Pat. No. 8,916,566 on Dec. 23, 2014, which claims the benefit ofU.S. Provisional Application No. 61/202,207, filed Feb. 5, 2009 and U.S.Provisional Application No. 61/213,927, filed Jul. 30, 2009.

TECHNICAL FIELD

The present invention relates to pyridazinone compounds.

BACKGROUND OF THE INVENTION

Phosphodiesterases (PDEs) are a superfamily of enzymes encoded by 21genes and subdivided into 11 distinct families according to structuraland functional properties. These enzymes metabolically inactivate theubiquitous intracellular second messengers, cyclic adenosinemonophosphate (cAMP) and cyclic guanosine monophosphate (cGMP); PDEsselectively catalyze the hydrolysis of the 3′-ester bond, forming theinactive 5′-monophosphate. On the basis of substrate specificity, thePDE families can be further classified into three groups: i) thecAMP-PDEs (PDE4, PDE7, PDE8), ii) the cGMP-PDEs (PDE5, PDE6 and PDE9),and iii) the dual-substrate PDEs (PDE1, PDE2, PDE3, PDE10 and PDE11).

The cAMP and cGMP are involved in the regulation of virtually everyphysiological process such as pro-inflammatory mediator production andaction, ion channel function, muscle relaxation, learning and memoryformation, differentiation, apoptosis, lipogenesis, glycogenolysis andgluconeogenesis. Especially, in neurons, these second messengers haveimportant role in the regulation of synaptic transmission as well as inneuronal differentiation and survival (Nat. Rev. Drug Discov. 2006, vol.5: 660-670). Regulation of these processes by cAMP and cGMP areaccompanied by activation of protein kinase A (PKA) and protein kinase G(PKG), which in turn phosphorylate a variety of substrates, includingtranscription factors, ion channels and receptors that regulate avariety of physiological processes. Intracellular cAMP and cGMPconcentrations seem to be temporally, spatially, and functionallycompartmentalized by regulation of adenyl and guanyl cyclases inresponse to extracellular signaling and their degradation by PDEs (Circ.Res. 2007, vol. 100(7): 950-966). PDEs provide the only means ofdegrading the cyclic nucleotides cAMP and cGMP in cells, thus PDEs playan essential role in cyclic nucleotide signaling. Thereby, PDEs could bepromising targets for various therapeutic drugs.

Phosphodiesterase 10A (PDE10A) was discovered in 1999 by threeindependent groups (Proc. Natl. Acad. Sci. USA 1999, vol. 96: 8991-8996,J. Biol. Chem. 1999, vol. 274: 18438-18445, Gene 1999, vol. 234:109-117). Expression studies have shown that PDE10A has the mostrestricted distribution within the all known PDE families; the PDE10AmRNA is highly expressed only in brain and testes (Eur. J. Biochem.1999, vol. 266: 1118-1127, J. Biol. Chem. 1999, vol. 274: 18438-18445).In the brain, mRNA and protein of PDE10A are highly enriched in mediumspiny neurons (MSNs) of the striatum (Eur. J. Biochem. 1999, vol. 266:1118-1127, Brain Res. 2003, vol. 985: 113-126). MSNs are classified intotwo groups: the MSN that express D₁ dopamine receptors responsible for adirect (striatonigral) pathway and the MSN that express D₂ dopaminereceptors responsible for an indirect (striatopallidal) pathway. Thefunction of direct pathway is to plan and execution, while indirectpathway is to act as a brake on behavioral activation. As PDE10Aexpresses in both MSNs, PDE10A inhibitors could activate both of thesepathways. The antipsychotic efficacy of current medications, D₂ orD₂/5-HT_(2A) antagonists, mainly derives from their activation of theindirect pathway in the striatum. As PDE10A inhibitors are able toactivate this pathway, this suggests that PDE10A inhibitors arepromising as antipsychotic drugs. The excessive D₂ receptor antagonismin the brain by D₂ antagonists causes problems of extrapyramidal sideeffects and hyperprolactinaemia. However the expression of PDE10A islimited to these striatal pathways in the brain, thus side effects byPDE10A inhibitors were expected to be weaker compared with current D₂antagonists. Regarding hyperprolactinaemia, PDE10A inhibitors wouldproduce no prolactin elevation due to lack of D₂ receptor antagonism inthe pituitary. Moreover, the presence of PDE10A in a direct pathwaymakes it likely that PDE10A inhibition will have some advantage overcurrent D₂ antagonists; the direct pathway is thought to promote desiredaction, and activation of this pathway by PDE10A inhibitors maycounteract extrapyramidal symptoms induced by excessive D₂ receptorantagonism. In addition, activation of this pathway could facilitatestriatal-thalamic outflow, promoting the execution of proceduralstrategies. Furthermore, enhancement of second messenger levels withoutblockade of dopamine and/or other neurotransmitter receptors may alsoprovide therapeutic advantages with fewer adverse side-effects comparedwith current antipsychotics (e.g., hyperprolactinaemia and weight gain).This unique distribution and function in the brain indicates that PDE10Arepresents an important new target for the treatment of neurological andpsychiatric disorders, in particular psychotic disorders likeschizophrenia.

As a phosphodiesterase (PDE)10 inhibitor, a compound represented by theformula:

-   -   wherein Z is

-   -   was disclosed in WO2006/072828 Pamphlet.

Further, as a phosphodiesterase (PDE)10 inhibitor, a compoundrepresented by the general formula

was also disclosed in WO2008/001182 Pamphlet.

SUMMARY OF INVENTION Technical Problem

However, development of new phosphodiesterase (PDE)10A inhibitors isfurther requested.

Solution to Problem

The present inventors discovered that a compound expressed by theformula (I_(o)) or a salt thereof (referred to as compound (I_(o)) inthis specification) has a PDE 10A inhibitory action and after extensiveinvestigation, completed the present invention.

Among the compounds (I_(o)), the compound represented by the formula (I)or a salt thereof (referred to as compound (I) in this specification) isa novel compound.

In this specification, the compound (I_(o)) including the compound (I)or a prodrug thereof is also referred to the compound of the presentinvention.

That is, the present invention provides the following features.

[1]

A compound of formula (I):

wherein

R¹ represents

a substituent,

R² represents

a hydrogen atom, or a substituent,

R³ represents

a hydrogen atom, or a substituent,

Ring A represents

an aromatic ring which can be substituted, and

Ring B represents

a 5-membered heteroaromatic ring which can be substituted;

provided that the following compounds:

-   1-(2-chlorophenyl)-6-methyl-3-{5-thioxo-4-[3-(trifluoromethyl)phenyl]-4,5-dihydro-1H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-[4-(2-fluorophenyl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl]-6-methylpyridazin-4(1H)-one,-   1-(4-chlorophenyl)-6-methyl-3-{5-thioxo-4-[3-(trifluoromethyl)phenyl]-4,    5-dihydro-1H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-[4-(2-fluorophenyl)-5-(methylsulfanyl)-4H-1,2,4-triazol-3-yl]-6-methylpyridazin-4(1H)-one,-   1-(4-Chlorophenyl)-6-methyl-3-{5-(methylsulfanyl)-4-[3-(trifluoromethyl)phenyl]-4H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   1-(2-chlorophenyl)-6-methyl-3-{5-(methyl    sulfanyl)-4-[3-(trifluoromethyl)phenyl]-4H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   3-(3,5-dimethyl-1H-pyrazol-1-yl)-1-phenylpyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-{1-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]-1H-pyrazol-5-yl}pyridazin-4(1H)-one,-   3-[1-(2-fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-chlorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(4-methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-nitrophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(1,1-dioxidotetrahydrothiophen-3-yl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(4-methylphenyl)-1H-pyrazol-5-yl]-1-phenylpyridazin-4(1H)-one,-   3-[1-(4-chlorophenyl)-1H-pyrazol-5-yl]-1-phenylpyridazin-4(1H)-one,-   3-(4-ethyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-1-(4-methylphenyl)pyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-{1-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]-1H-pyrazol-3-yl}pyridazin-4(1H)-one,-   3-[1-(2-fluorophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-chlorophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-methoxyphenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-(1-phenyl-1H-pyrazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-nitrophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(4-methylphenyl)-1H-pyrazol-3-yl]-1-phenylpyridazin-4(1H)-one,-   3-[1-(4-chlorophenyl)-1H-pyrazol-3-yl]-1-phenylpyridazin-4(1H)-one,

a compound of formula:

wherein

Ring A′ is a benzene ring which can be substituted by one substituentselected from a halogen atom, and an alkyl group,

R^(1′) is

(1) an ethyl group, or

(2) a phenyl group which can be substituted by one or more substituentsselected from a fluorine atom, and a trifluoromethyl group,

R^(3′) is a hydrogen atom, or a methyl group, and

Ra is a hydrogen atom, or a C₁₋₄ acyclic hydrocarbon group which can besubstituted,

a compound of formula:

wherein

Ring A″ is a benzene ring which can be substituted by halogen, and

R^(1″) is an acyl group

are excluded;

or a salt thereof.

[2]

The compound according to the above-mentioned [1] or [2], wherein

R² represents

a halogen atom, a hydroxy group, a C₁₋₁₀ alkyl group which can besubstituted, or a C₁₋₁₀ alkoxy group which can be substituted.

[3]

The compound according to the above-mentioned [1] or [2], wherein

R² represents

a C₁₋₁₀ alkoxy group which can be substituted by one or moresubstituents selected from a halogen atom, a C₁₋₁₀ alkoxy group, and aC₃₋₇ cycloalkyl group.

[4]

The compound according to the above-mentioned [1] or [2], wherein

R² represents

a C₁₋₁₀ alkoxy group.

[5]

The compound according to any one of the above-mentioned [1] to [4],wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 substituents selectedfrom a halogen atom, a C₁₋₁₀ alkyl group which can be substituted, and aC₁₋₁₀ alkoxy group which can be substituted.

[6]

The compound according to any one of the above-mentioned [1] to [5],wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 substituents selectedfrom a halogen atom, a C₁₋₁₀ alkyl group, and a C₁₋₁₀ alkoxy group.

[7]

The compound according to any one of the above-mentioned [1] to [6],wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 halogen atoms.

[8]

The compound according to any one of the above-mentioned [1] to [7],wherein

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group which can be substituted.

[9]

The compound according to any one of the above-mentioned [1] to [8],wherein

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group.

[10]

The compound according to any one of the above-mentioned [1] to [9],wherein

R³ represents

a hydrogen atom.

[11]

The compound according to any one of the above-mentioned [1] to [10],wherein

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted,

(5) a C₁₋₁₀ alkylsulfonyl group which can be substituted,

(6) a C₃₋₇ cycloalkyl group which can be substituted,

(7) a cyano group,

(8) a carbamoyl group which can be substituted,

(9) a C₁₋₁₀ alkylsulfonyloxy group which can be substituted,

(10) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group which can be substituted,

(11) a tetrahydropyranyl group which can be substituted,

(12) a dihydropyranyl group which can be substituted,

(13) a mono-(C₁₋₁₀ alkyl-carbonyl)-amino group which can be substituted,

(14) a C₁₋₁₀ alkoxy-carbonyl group which can be substituted,

(15) a C₁₋₁₀ alkylsulfinyl group which can be substituted, and

(16) a C₁₋₁₀ alkylsulfanyl group which can be substituted.

[12]

The compound according to any one of the above-mentioned [1] to [11],wherein

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by oneor more substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted, and a C₁₋₁₀ alkyl group which can be substituted.

[13]

The compound according to any one of the above-mentioned [1] to [12],wherein

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted by 1 to 3 halogenatoms,

(3) a C₁₋₁₀ alkoxy group which can be substituted by 1 to 3 halogenatoms,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by 1to 4 substituents selected from a halogen atom, a hydroxy group, an oxogroup, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which can besubstituted by halogen, and a C₁₋₁₀ alkyl group which can be substitutedby halogen.

[14]

The compound according to any one of the above-mentioned [1] to [13],wherein

Ring A represents

a benzene ring which is substituted with

(1) (i) 1 or 2 halogen atoms, or (ii) one C₁₋₁₀ alkoxy group, and

(2) one 4- to 6-membered heterocyclic group containing 0 or 1 oxygenatom, and 1 to 3 nitrogen atoms as heteroatoms which can be substitutedby 1 to 4 substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted by halogen, and a C₁₋₁₀ alkyl group which can besubstituted by halogen.

[15]

The compound according to the above-mentioned [14], wherein

the 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms represents

a morpholino group, a pyrrolyl group, a dihydropyrrolyl group, apyrazolyl group, a dihydropyrazolyl group, a piperidyl group, anazetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group or an imidazolidinyl group.

[16]

The compound according to any one of the above-mentioned [1] to [15],wherein

Ring B represents

an imidazole ring, a pyrazole ring, a triazole ring or a tetrazole ring,each of which can be further substituted with 1 to 3 substituentsselected from a halogen atom, and a C₁₋₁₀ alkyl group which can besubstituted by halogen.

[17]

The compound according to any one of the above-mentioned [1] to [16],wherein

Ring B represents

a pyrazole ring which can be further substituted with 1 to 3substituents selected from a halogen atom, and a C₁₋₁₀ alkyl group whichcan be substituted by halogen.

[18]

The compound according to any one of the above-mentioned [1] to [17],wherein

Ring B represents

a pyrazole ring.

[19]

The compound according to the above-mentioned [2], wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 substituents selectedfrom a halogen atom, a C₁₋₁₀ alkyl group which can be substituted, and aC₁₋₁₀ alkoxy group which can be substituted,

R² represents

a halogen atom, a hydroxy group, a C₁₋₁₀ alkyl group which can besubstituted, or a C₁₋₁₀alkoxy group which can be substituted,

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group which can be substituted,

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted,

(5) a C₁₋₁₀ alkylsulfonyl group which can be substituted,

(6) a C₃₋₇ cycloalkyl group which can be substituted,

(7) a cyano group,

(8) a carbamoyl group which can be substituted,

(9) a C₁₋₁₀ alkylsulfonyloxy group which can be substituted,

(10) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group which can be substituted,

(11) a tetrahydropyranyl group which can be substituted,

(12) a dihydropyranyl group which can be substituted,

(13) a mono-(C₁₋₁₀alkyl-carbonyl)-amino group which can be substituted,

(14) a C₁₋₁₀ alkoxy-carbonyl group which can be substituted,

(15) a C₁₋₁₀ alkylsulfinyl group which can be substituted, and

(16) a C₁₋₁₀ alkylsulfanyl group which can be substituted, and

Ring B represents

an imidazole ring, a pyrazole ring, a triazole ring or a tetrazole ring,each of which can be further substituted with 1 to 3 substituentsselected from a halogen atom, and a C₁₋₁₀alkyl group which can besubstituted by halogen.

[20]

The compound according to the above-mentioned [19], wherein.

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by oneor more substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted, and a C₁₋₁₀ alkyl group which can be substituted.

[21]

The compound according to the above-mentioned [2], wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 substituents selectedfrom a halogen atom, a C₁₋₁₀ alkyl group, and a C₁₋₁₀ alkoxy group,

R² represents

a C₁₋₁₀ alkoxy group which can be substituted by one or moresubstituents selected from a halogen atom, a C₁₋₁₀ alkoxy group, and aC₃₋₇ cycloalkyl group,

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group,

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted by 1 to 3 halogenatoms,

(3) a C₁₋₁₀ alkoxy group which can be substituted by 1 to 3 halogenatoms,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by 1to 4 substituents selected from a halogen atom, a hydroxy group, an oxogroup, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀alkoxy group which can besubstituted by halogen, and a C₁₋₁₀ alkyl group which can be substitutedby halogen,

Ring B represents

a pyrazole ring which can be further substituted with 1 to 3substituents selected from a halogen atom, and a C₁₋₁₀ alkyl group whichcan be substituted by halogen.

[22]

The compound according to the above-mentioned [2], wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 halogen atoms,

R² represents

a C₁₋₁₀ alkoxy group,

R³ represents

a hydrogen atom,

Ring A represents

a benzene ring which is substituted with

(1) (i) 1 or 2 halogen atoms, or (ii) one C₁₋₁₀ alkoxy group, and

(2) one 4- to 6-membered heterocyclic group containing 0 or 1 oxygenatom, and 1 to 3 nitrogen atoms as heteroatoms which can be substitutedby 1 to 4 substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted by halogen, and a C₁₋₁₀ alkyl group which can besubstituted by halogen,

Ring B represents

a pyrazole ring.

[23]

The compound according to the above-mentioned [22], wherein

the 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms represents

a morpholino group, a pyrrolyl group, a dihydropyrrolyl group, apyrazolyl group, a dihydropyrazolyl group, a piperidyl group, anazetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group or an imidazolidinyl group.

[24]

The compound according to the above-mentioned [1], wherein

R¹ represents

an aromatic group which can be substituted,

Ring A represents

an aromatic ring which is substituted with

(a) one substituent selected from

(1) a C₃₋₇ cycloalkyl group which can be substituted, and

(2) a 4- to 6-membered heterocyclic group containing 1 to 5 heteroatomsselected from a nitrogen atom, a sulfur atom, and an oxygen atom whichcan be substituted, and

(b) one or more further substituents.

[25]

The compound according to the above-mentioned [24], wherein

R¹ represents

a phenyl group which can be substituted,

R² represents

a hydrogen atom, a halogen atom, a hydroxy group, a C₁₋₁₀ alkyl groupwhich can be substituted, or a C₁₋₁₀ alkoxy group which can besubstituted,

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group which can be substituted,

Ring A represents

a benzene ring which

is substituted with one substituent selected from

(1) a C₃₋₇ cycloalkyl group which can be substituted,

(2) a dihydropyranyl group which can be substituted,

(3) a tetrahydropyranyl group which can be substituted, and

(4) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted,

and can be substituted by further substituents, and

Ring B represents

an imidazole ring, a pyrazole ring, a triazole ring, a tetrazole ring,an isoxazole ring, an 1,3-oxazole ring, a furan ring, or a thiophenering, each of which can be substituted.

[26]

The compound according to the above-mentioned [25], wherein

the 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms represents

a morpholino group, a pyrrolyl group, a dihydropyrrolyl group, apyrazolyl group, a dihydropyrazolyl group, a piperidyl group, anazetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group, an imidazolidinyl group, an isoxazolyl group, apyridyl group, a piperazinyl group, or a thiazolyl group.

[27]

The compound according to the above-mentioned [24], wherein

the further substituents are 1 to 4 substituents selected from

(1) a halogen atom,

(2) an oxo group,

(3) a hydroxy group,

(4) a C₁₋₁₀ alkyl group which can be substituted,

(5) a C₁₋₁₀ alkoxy group which can be substituted,

(6) a C₁₋₁₀alkylsulfonyl group,

(7) a morpholin-4-yl sulfonyl group,

(8) a cyano group,

(9) a carbamoyl group,

(10) a halogeno C₁₋₁₀alkylsulfonyloxy group,

(11) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group,

(12) a di-C₁₋₁₀ alkyl-amino group,

(13) a mono-(C₁₋₁₀alkyl-carbonyl)-amino group,

(14) a C₁₋₁₀alkoxy-carbonyl group,

(15) a phenoxy group,

(16) a C₁₋₁₀ alkylsulfinyl group,

(17) a di-C₁₋₁₀ alkyl-amino group,

(18) a benzimidazole-2-yloxy group, and

(19) a benzimidazole-2-yl sulfonyl group.

[28]

The compound according to the above-mentioned [24], wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 halogen atoms,

R² represents

a hydrogen atom or a C₁₋₁₀ alkoxy group,

R³ represents

a hydrogen atom,

Ring A represents

a benzene ring,

which is substituted with one 4- to 6-membered heterocyclic groupcontaining 0 or 1 oxygen atom, and 1 to 3 nitrogen atoms as heteroatomswhich can be substituted by 1 to 4 substituents selected from a halogenatom, a hydroxy group, an oxo group, halogeno C₁₋₁₀ alkoxy group, aC₁₋₁₀ alkoxy-carbonyl, and a C₁₋₁₀ alkyl group which can be substitutedby halogen,

and which can be further substituted with 1 or 2 substituents selectedfrom a halogen atom and a C₁₋₁₀ alkoxy group, and

Ring B represents

a pyrazole ring.

[29]

The compound according to the above-mentioned [28], wherein

the 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms represents

a morpholino group, a pyrrolyl group, a dihydropyrrolyl group, apyrazolyl group, a dihydropyrazolyl group, a piperidyl group, anazetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group or an imidazolidinyl group.

[30]

-   1-[2-fluoro-4-(3,3,4,4-tetrafluoropyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[31]

-   1-[2-fluoro-4-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[32]

-   1-[4-(3,4-difluoro-1H-pyrrol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[33]

-   1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[34]

-   1-[4-(4-chloro-1H-pyrazol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[35]

-   1-[2-fluoro-4-(2-oxo-1,3-oxazolidin-3-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof

[36]

-   3-[1-(2-fluorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one,    or a salt thereof.

[37]

-   3-[1-(3-chlorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one,    or a salt thereof.

[38]

-   1-[4-(4,4-dimethyl-2-oxopyrrolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[39]

-   1-[4-(5,5-dimethyl-2-oxo-1,3-oxazolidin-3-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[40]

-   5-methoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

[41]

A prodrug of the compound according to according to any one of theabove-mentioned [1] to [40]

[42]

A medicament comprising the compound according to according to any oneof the above-mentioned [1] to [40] or a prodrug thereof.

[43]

A medicament comprising a compound of formula (I₀):

wherein

R¹ represents

a substituent,

R² represents

a hydrogen atom, or a substituent,

R³ represents

a hydrogen atom, or a substituent,

Ring A represents

an aromatic ring which can be substituted, and

Ring B represents

a 5-membered heteroaromatic ring which can be substituted,

or a salt thereof, or a prodrug thereof.

[44]

The medicament according to the above-mentioned [43] which is an agentfor inhibiting phosphodiesterase 10A.

[45]

The medicament according to the above-mentioned [43] which is forpreventing or treating schizophrenia.

[46]

A method of preventing or treating schizophrenia comprisingadministrating an effective amount of a compound of formula (I₀):

wherein

R¹ represents

a substituent,

R² represents

a hydrogen atom, or a substituent,

R³ represents

a hydrogen atom, or a substituent,

Ring A represents

an aromatic ring which can be substituted, and

Ring B represents

a 5-membered heteroaromatic ring which can be substituted,

or a salt thereof, or a prodrug thereof

to a mammal.

[47]

Use of a compound of formula (I₀):

wherein

R¹ represents

a substituent,

R² represents

a hydrogen atom, or a substituent,

R³ represents

a hydrogen atom, or a substituent,

Ring A represents

an aromatic ring which can be substituted, and

Ring B represents

a 5-membered heteroaromatic ring which can be substituted,

or a salt thereof, or a prodrug thereof

as a medicament.

[48]

Use of a compound of formula (I₀):

wherein

R¹ represents

a substituent,

R² represents

a hydrogen atom, or a substituent,

R³ represents

a hydrogen atom, or a substituent,

Ring A represents

an aromatic ring which can be substituted, and

Ring B represents

a 5-membered heteroaromatic ring which can be substituted,

or a salt thereof, or a prodrug thereof

in the manufacture of a medicament for preventing or treatingschizophrenia.

Besides, the present invention also provides the following features.

[1′]

A compound represented by the formula (I):

wherein

R¹ represents a substituent,

R² represents a hydrogen atom or a substituent,

R³ represents a hydrogen atom or a substituent,

Ring A represents an aromatic ring which can be substituted, and

Ring B represents a 5-membered aromatic heterocyclic ring which can besubstituted;

provided that the following compounds are excluded:

a compound represented by the formula:

wherein

Ring A′ represents a benzene ring which can be substituted by onesubstituent selected from halogen and alkyl,

R^(1′) represents (1) ethyl or (2) phenyl which can be substituted byone or more substituents selected from fluorine and trifluoromethyl,

R^(3′) represents hydrogen or methyl, and

Ra represents a hydrogen atom or a C₁₋₄ acyclic hydrocarbon group whichcan be substituted; and

a compound represented by the formula:

wherein

Ring A″ represents a benzene ring which can be substituted by halogen,and

R^(1″) represents an acyl group;

or a salt thereof.

[2′]

A prodrug of the compound described as in the above-mentioned [1′].

[3′]

A medicament comprising the compound described as in the above-mentioned[1′] or the prodrug thereof.

[4′]

A medicament comprising a compound represented by the formula (I_(o)):

wherein

R¹ represents a substituent,

R² represents a hydrogen atom or a substituent,

R³ represents a hydrogen atom or a substituent,

Ring A represents an aromatic ring which can be substituted, and

Ring B represents a 5-membered aromatic heterocyclic ring which can besubstituted,

or a salt thereof.

[5′]

The medicament described as in the above-mentioned [4′] which is anagent for inhibiting phosphodiesterase 10A.

[6′]

The medicament described as in the above-mentioned [4′] which is forpreventing or treating schizophrenia.

[7′]

A method for preventing or treating schizophrenia which comprisesadministering an effective amount of a compound represented by theformula (I_(o)):

wherein

R¹ represents a substituent,

R² represents a hydrogen atom or a substituent,

R³ represents a hydrogen atom or a substituent,

Ring A represents an aromatic ring which can be substituted, and

Ring B represents a 5-membered aromatic heterocyclic ring which can besubstituted,

or a salt thereof.

[8′]

Use of a compound represented by the formula (I_(o)):

wherein

R¹ represents a substituent,

R² represents a hydrogen atom or a substituent,

R³ represents a hydrogen atom or a substituent,

Ring A represents an aromatic ring which can be substituted, and

Ring B represents a 5-membered aromatic heterocyclic ring which can besubstituted,

or a salt thereof

as a medicament.

[9′]

Use of a compound represented by the formula (I_(o)):

wherein

R¹ represents a substituent,

R² represents a hydrogen atom or a substituent,

R³ represents a hydrogen atom or a substituent,

Ring A represents an aromatic ring which can be substituted, and

Ring B represents a 5-membered aromatic heterocyclic ring which can besubstituted,

or a salt thereof

in the manufacture of a medicament for preventing or treatingschizophrenia.

Advantageous Effects of Invention

The compound of the present invention has a PDE inhibitory activity andis useful as a drug for preventing or treating schizophrenia, etc.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A and FIG. 1B. Graphs showing dose-dependent elevation of cAMP(FIG. 1A) and cGMP (FIG. 1B) contents in the mouse striatum by compoundA. All data were represented as means plus the standard errors of themeans (n=5-7) and analyzed using a williams' test with significance setat #P<0.025. The phrase (mg/kg, i.p.) means (milligram per kilogram,intraperitoneal treatment). The phrase (pmol/mg tissue) means (picomoleper milligram tissue).

FIG. 2A. A graph showing dose-dependent inhibition of methamphetamine(MAP)-induced hyperlocomotion by compound A.

FIG. 2B. A graph showing dose-dependent inhibition of MK-801-inducedhyperlocomotion by compound A.

In FIGS. 2A and 2B, the compound A decreased spontaneous locomotion(−30-0 min). All data were represented as means plus the standard errorsof the means (n=5-8) and analyzed using a williams' test withsignificance set at #P<0.025. The phrase (mg/kg, i.p.) means (milligramper kilogram, intraperitoneal treatment).

FIG. 3. A graph showing reversal of MK-801-induced PPI deficits at 82 dBprepulse by compound A. All data were represented as means plus thestandard errors of the means (n=8-11) and dose-dependency was analyzedusing a williams' test with significance set at #P<0.025.

*P<0.05, Student's t-test as compared to control group. $P<0.05,Student's t-test as compared to MK-801-treated group. The phrase (mg/kg,i.p.) means (milligram per kilogram, intraperitoneal treatment).

FIG. 4. A graph showing inhibition of MK-801-induced hyperlocomotion bycompounds in mice. All data were represented as means plus the standarderrors of the means (n=5-8) and analyze using Dunnett's t-test withsignificance set at *P<0.0205.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be explained in detail below.

Unless otherwise specifically stated, in this specification, examples ofthe “halogen” include fluorine, chlorine, bromine and iodine.

Unless otherwise specifically stated, in this specification, the phrase“can be halogenated” or the term “halogeno” means that one or more(e.g., 1 to 3) halogen atoms can be present as substituents.

Unless otherwise specifically stated, in this specification, examples ofthe “alkyl (group)” include C₁₋₁₀ alkyl (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkyl (group)” include methyl, ethyl, propyl, isopropyl,butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl,and hexyl.

Unless otherwise specifically stated, in this specification, the term“C₁₋₁₀ alkyl (group) that can be halogenated” means C₁₋₁₀ alkyl (group)which can be substituted by halogen, and examples thereof includetrifluoromethyl.

Unless otherwise specifically stated, in this specification, examples ofthe “alkenyl (group)” include C₂₋₆ alkenyl (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₂₋₆ alkenyl (group)” include vinyl, 1-propen-1-yl, 2-propen-1-yl,isopropenyl, 2-buten-1-yl, 4-penten-1-yl, and 5-hexen-1-yl.

Unless otherwise specifically stated, in this specification, examples ofthe “alkynyl (group)” include C₂₋₆ alkynyl (group).

Examples of “C₂₋₆ alkynyl (group)” include ethynyl, 1-propyn-1-yl,2-propyn-1-yl, 4-pentyn-1-yl, and 5-hexyn-1-yl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyl-C₂₋₆ alkynyl (group)” include cyclopropylethyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyl (group)” include cyclopropyl, cyclobutyl,cyclopentyl, and cyclohexyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryl (group)” include phenyl, 1-naphthyl, 2-naphthyl,2-biphenylyl, 3-biphenylyl, 4-biphenylyl, and 2-anthryl.

Unless otherwise specifically stated, in this specification, examples of“C₇₋₁₆ aralkyl (group)” include benzyl, phenethyl, diphenylmethyl,1-naphthylmethyl, 2-naphthylmethyl, 2,2-diphenylethyl, 3-phenylpropyl,4-phenylbutyl, 5-phenylpentyl, 2-biphenylmethyl, 3-biphenylmethyl, and4-biphenylmethyl.

Unless otherwise specifically stated, in this specification, examples of“C₆₋₁₄ aryl-C₂₋₆ alkenyl (group)” include styryl.

Unless otherwise specifically stated, in this specification, the“heterocyclic group” (and a heterocyclic moiety in a substituent) is anon-aromatic heterocyclic group, or a heteroaryl group (i.e., aromaticheterocyclic group), and examples thereof include 3- to 14-memberedheterocyclic group having 1 to 5 hetero atoms selected from nitrogen,sulfur and oxygen. This “heterocyclic group” can be monocyclic, bicyclicor tricyclic.

Examples of the “3- to 14-membered heterocyclic group” include 3- to14-membered aromatic heterocyclic group having 1 to 5 hetero atomsselected from nitrogen, sulfur and oxygen such as pyrrolyl (e.g.,1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl), furyl (e.g., 2-furyl, 3-furyl),thienyl (e.g., 2-thienyl, 3-thienyl), pyrazolyl (e.g., 1-pyrazolyl,3-pyrazolyl, 4-pyrazolyl), imidazolyl (e.g., 1-imidazolyl, 2-imidazolyl,4-imidazolyl), isoxazolyl (e.g., 3-isoxazolyl, 4-isoxazolyl,5-isoxazolyl), oxazolyl (e.g., 2-oxazolyl, 4-oxazolyl, 5-oxazolyl),isothiazolyl (e.g., 3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl),thiazolyl (e.g., 2-thiazolyl, 4-thiazolyl, 5-thiazolyl), triazolyl(e.g., 1, 2, 3-triazol-4-yl, 1, 2, 4-triazol-3-yl), oxadiazolyl (e.g.,1, 2, 4-oxadiazol-3-yl, 1, 2, 4-oxadiazol-5-yl), thiadiazolyl (e.g., 1,2, 4-thiadiazol-3-yl, 1, 2, 4-thiadiazol-5-yl), tetrazolyl, pyridyl(e.g., 2-pyridyl, 3-pyridyl, 4-pyridyl), pyridazinyl (e.g.,3-pyridazinyl, 4-pyridazinyl), pyrimidinyl (e.g., 2-pyrimidinyl,4-pyrimidinyl, 5-pyrimidinyl), pyrazinyl, indolyl, isoindolyl (e.g.,1-isoindolyl, 2-isoindolyl, 3-isoindolyl, 4-isoindolyl, 5-isoindolyl,6-isoindolyl, 7-isoindolyl), indolyl (e.g., 1-indolyl, 2-indolyl,3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl, 7-indolyl), benzo[b]furanyl(e.g., 2-benzo[b]furanyl, 3-benzo[b]furanyl, 4-benzo[b]furanyl,5-benzo[b]furanyl, 6-benzo[b]furanyl, 7-benzo[b]furanyl),benzo[c]furanyl (e.g., 1-benzo[c]furanyl, 4-benzo[c]furanyl,5-benzo[c]furanyl), benzo[b]thienyl (e.g., 2-benzo[b]thienyl,3-benzo[b]thienyl, 4-benzo[b]thienyl, 5-benzo[b]thienyl,6-benzo[b]thienyl, 7-benzo[b]thienyl), benzo[c]thienyl (e.g.,1-benzo[c]thienyl, 4-benzo[c]thienyl, 5-benzo[c]thienyl), indazolyl(e.g., 1-indazolyl, 2-indazolyl, 3-indazolyl, 4-indazolyl, 5-indazolyl,6-indazolyl, 7-indazolyl), benzimidazolyl (e.g., 1-benzimidazolyl,2-benzimidazolyl, 4-benzimidazolyl, 5-benzimidazolyl), 1,2-benzoisoxazolyl (e.g., 1, 2-benzisoxazol-3-yl, 1, 2-benzisoxazol-4-yl,1, 2-benzisoxazol-5-yl, 1, 2-benzisoxazol-6-yl, 1, 2-benzisoxazol-7-yl),benzoxazolyl(e.g., 2-benzoxazolyl, 4-benzoxazolyl, 5-benzoxazolyl,6-benzoxazolyl, 7-benzoxazolyl), 1, 2-benzoisothiazolyl (e.g., 1,2-benzisothiazol-3-yl, 1, 2-benzisothiazol-4-yl, 1,2-benzisothiazol-5-yl, 1, 2-benzisothiazol-6-yl, 1,2-benzisothiazol-7-yl), benzothiazolyl (e.g., 2-benzothiazolyl,4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl),isoquinolyl (e.g., 1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl,5-isoquinolyl), quinolyl (e.g., 2-quinolyl, 3-quinolyl, 4-quinolyl,5-quinolyl, 8-quinolyl), cinnolinyl (e.g., 3-cinnolinyl, 4-cinnolinyl,5-cinnolinyl, 6-cinnolinyl, 7-cinnolinyl, 8-cinnolinyl), phthalazinyl(e.g., 1-phthalazinyl, 4-phthalazinyl, 5-phthalazinyl, 6-phthalazinyl,7-phthalazinyl, 8-phthalazinyl), quinazolinyl (e.g., 2-quinazolinyl,4-quinazolinyl, 5-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl,8-quinazolinyl), quinoxalinyl (e.g., 2-quinoxalinyl, 3-quinoxalinyl,5-quinoxalinyl, 6-quinoxalinyl, 7-quinoxalinyl, 8-quinoxalinyl),pyrazolo[1,5-a]pyridyl (e.g., pyrazolo[1,5-1]pyridin-2-yl,pyrazolo[1,5-a]pyridin-3-yl, pyrazolo[1,5-a]pyridin-4-yl,pyrazolo[1,5-a]pyridin-5-yl, pyrazolo[1,5-a]pyridin-6-yl,pyrazolo[1,5-a]pyridin-7-yl), imidazo[1,2-a]pyridyl (e.g.,imidazo[1,2-a]pyridin-2-yl, imidazo[1,2-a]pyridin-3-yl,imidazo[1,2-a]pyridin-5-yl, imidazo[1,2-a]pyridin-6-yl,imidazo[1,2-a]pyridin-7-yl, imidazo [1,2-a]pyridin-8-yl); and

saturated or unsaturated 3- to 14-membered non-aromatic heterocyclicgroup having 1 to 5 hetero atoms selected from nitrogen, sulfur andoxygen such as tetrahydrofuryl, oxazolidinyl, imidazolinyl (e.g.,1-imidazolinyl, 2-imidazolinyl, 4-imidazolinyl), aziridinyl (e.g.,1-aziridinyl, 2-aziridinyl), azetidinyl (e.g., 1-azetidinyl,2-azetidinyl), pyrrolidinyl (e.g., 1-pyrrolidinyl, 2-pyrrolidinyl,3-pyrrolidinyl), piperidinyl (e.g., 1-piperidinyl, 2-piperidinyl,3-piperidinyl), azepanyl (e.g., 1-azepanyl, 2-azepanyl, 3-azepanyl,4-azepanyl), azocanyl (e.g., 1-azocanyl, 2-azocanyl, 3-azocanyl,4-azocanyl), piperazinyl (e.g., 1, 4-piperazin-1-yl, 1,4-piperazin-2-yl), diazepinyl (e.g., 1, 4-diazepin-1-yl, 1,4-diazepin-2-yl, 1, 4-diazepin-5-yl, 1, 4-diazepin-6-yl), diazocanyl(e.g., 1, 4-diazocan-1-yl, 1, 4-diazocan-2-yl, 1, 4-diazocan-5-yl, 1,4-diazocan-6-yl, 1, 5-diazocan-1-yl, 1, 5-diazocan-2-yl, 1,5-diazocan-3-yl), tetrahydropyranyl (e.g., tetrahydropyran-4-yl),morpholinyl (e.g., 4-morpholinyl), thiomorpholinyl (e.g.,4-thiomorpholinyl), 2-oxazolidinyl, dihydrofuryl, dihydropyranyl, anddihydroquinolyl.

Unless otherwise specifically stated, in this specification, examples ofthe “5- to 10-membered heterocyclic groups” include those having 5- to10-members among the aforementioned “3- to 14-membered heterocyclicgroup”.

Unless otherwise specifically stated, in this specification, examples ofthe “aromatic heterocyclic group” (and an aromatic heterocyclic moietyin a substituent) include the “3- to 14-membered aromatic heterocyclicgroup having 1 to 5 hetero atoms selected from nitrogen, sulfur andoxygen” as exemplified above as said “heterocyclic group”.

Unless otherwise specifically stated, in this specification, examples ofthe “non-aromatic heterocyclic group” (and an aromatic heterocyclicmoiety in a substituent) include the “saturated or unsaturated 3- to14-membered non-aromatic heterocyclic group having 1 to 5 hetero atomsselected from nitrogen, sulfur and oxygen” as exemplified above as said“heterocyclic group”.

Unless otherwise specifically stated, in this specification, examples ofthe “saturated heterocyclic group” (and a saturated heterocyclic moietyin a substituent) include those saturated among said “non-aromaticheterocyclic group”. Specific examples thereof include tetrahydrofuryl,morpholinyl, thiomorpholinyl, piperidinyl, pyrrolidinyl, and piperazinylgroup.

Unless otherwise specifically stated, in this specification, examples ofthe “5- to 6-membered saturated heterocyclic group” (and a saturatedheterocyclic moiety in a substituent) include those having 5- to6-members among said “saturated heterocyclic group”.

Unless otherwise specifically stated, in this specification, examples ofthe “alkoxy (group)” include C₁₋₁₀ alkoxy (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkoxy (group)” include methoxy, ethoxy, propoxy, isopropoxy,butoxy, isobutoxy, sec-butoxy, pentyloxy and hexyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyloxy (group)” include cyclopropyloxy, cyclobutyloxy,cyclopentyloxy, cyclohexyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryloxy (group)” include phenyloxy, 1-naphthyloxy and2-naphthyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “C₇₋₁₆ aralkyloxy (group)” include benzyloxy and phenethyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “alkyl-carbonyloxy (group)” include C₁₋₁₀alkyl-carbonyloxy (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkyl-carbonyloxy (group)” include acetoxy and propionyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “alkoxy-carbonyloxy (group)” include C₁₋₁₀alkoxy-carbonyloxy(group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkoxy-carbonyloxy (group)” include methoxycarbonyloxy,ethoxycarbonyloxy, propoxycarbonyloxy and butoxycarbonyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “mono-alkyl-carbamoyloxy (group)” include mono-C₁₋₁₀alkyl-carbamoyloxy (group).

Unless otherwise specifically stated, in this specification, examples ofthe “mono-C₁₋₁₀ alkyl-carbamoyloxy (group)” include methylcarbamoyloxyand ethylcarbamoyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “di-alkyl-carbamoyloxy (group)” include di-C₁₋₁₀ alkyl-carbamoyloxy(group).

Unless otherwise specifically stated, in this specification, examples ofthe “di-C₁₋₁₀ alkyl-carbamoyloxy (group)” include dimethylcarbamoyloxyand diethylcarbamoyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryl-carbonyloxy (group)” include benzoyloxy andnaphthylcarbonyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “mono- or di-C₆₋₁₄ aryl-carbamoyloxy (group)” includephenylcarbamoyloxy and naphthylcarbamoyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe heterocyclic moiety of the “heterocyclic-oxy (group)” include thosesimilar to said “heterocyclic group” are included. Specifically,examples of the “heterocyclic-oxy (group)” include 5- to 14-memberedheterocyclic-oxy (group) having 1 to 5 hetero atoms selected fromnitrogen, sulfur and oxygen.

Unless otherwise specifically stated, in this specification, examples ofthe aromatic heterocyclic moiety of the “heterocyclic-oxy (group)”include those similar to the “aromatic heterocyclic group” as examplesof said “heterocyclic group”. Specifically, examples of the “aromaticheterocyclic-oxy (group)” include 3- to 14-membered aromaticheterocyclic-oxy (group) having 1 to 5 hetero atoms selected fromnitrogen, sulfur and oxygen.

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀alkylsulfonyloxy (group)” include methylsulfonyloxy andethylsulfonyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “halogeno C₁₋₁₀ alkylsulfonyloxy (group)” include halogenomethylsulfonyloxy and halogeno ethyl sulfonyloxy.

Unless otherwise specifically stated, in this specification, examples ofthe “alkylsulfanyl (group)” include C₁₋₁₀ alkylsulfanyl (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkylsulfanyl (group)” include methylsulfanyl, ethylsulfanyl,propylsulfanyl, isopropylsulfanyl, butylsulfanyl, sec-butylsulfanyl, andtert-butylsulfanyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkylsulfanyl (group)” include cyclopropylsulfanyl,cyclobutylsulfanyl, cyclopentylsulfanyl and cyclohexylsulfanyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ arylsulfanyl (group)” include phenylsulfanyl,1-naphthylsulfanyl and 2-naphthylsulfanyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₇₋₁₆ aralkylsulfanyl (group)” include benzylsufanyl andphenethylsulfanyl.

Unless otherwise specifically stated, in this specification, examples ofthe heterocyclic moiety of the “heterocyclic-sulfanyl (group)” includethose similar to said “heterocyclic group”. Specifically, examples ofthe “heterocyclic-sulfanyl (group)” include 5- to 14-memberedheterocyclic-sulfanyl (group) having 1 to 5 hetero atoms selected fromnitrogen, sulfur and oxygen.

Unless otherwise specifically stated, in this specification, examples ofthe “alkyl-carbonyl (group)” include C₁₋₁₀ alkyl-carbonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkyl-carbonyl (group)” include acetyl, propionyl andpivaloyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyl-carbonyl (group)” include cyclopropylcarbonyl,cyclopentylcarbonyl and cyclohexylcarbonyl group.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryl-carbonyl (group)” include benzoyl, 1-naphthoyl and2-naphthoyl group.

Unless otherwise specifically stated, in this specification, examples ofthe “C₇₋₁₆ aralkyl-carbonyl (group)” include phenylacetyl and3-phenylpropionyl group.

Unless otherwise specifically stated, in this specification, examples ofthe heterocyclic moiety of the “heterocyclic-carbonyl (group)” includethose similar to said “heterocyclic group”. Specifically, examplesthereof include 3- to 14-membered heterocyclic-carbonyl (group) having 1to 5 hetero atoms selected from nitrogen, sulfur and oxygen. Further,specific examples thereof include picolinoyl, nicotinoyl, isonicotinoyl,2-thenoyl, 3-thenoyl, 2-furoyl, 3-furoyl, 1-morpholinylcarbonyl,4-thiomorpholinylcarbonyl, aziridin-1-ylcarbonyl, aziridin-2-ylcarbonyl,azetidin-1-ylcarbonyl, azetidin-2-ylcarbonyl, pyrrolidine-1-ylcarbonyl,pyrrolidine-2-ylcarbonyl, pyrrolidine-3-ylcarbonyl,piperidine-1-ylcarbonyl, piperidine-2-ylcarbonyl,piperidine-3-ylcarbonyl, azepan-1-ylcarbonyl, azepan-2-ylcarbonyl,azepan-3-ylcarbonyl, azepan-4-ylcarbonyl, azocan-1-ylcarbonyl,azocan-2-ylcarbonyl, azocan-3-ylcarbonyl, azocan-4-ylcarbonyl, 1,4-piperazine-1-ylcarbonyl, 1, 4-piperazine-2-ylcarbonyl, 1,4-diazepan-1-ylcarbonyl, 1, 4-diazepan-2-ylcarbonyl, 1,4-diazepan-5-ylcarbonyl, 1, 4-diazepan-6-ylcarbonyl, 1,4-diazocan-1-ylcarbonyl, 1, 4-diazocan-2-ylcarbonyl, 1,4-diazocan-5-ylcarbonyl, 1, 4-diazocan-6-ylcarbonyl, 1,5-diazocan-1-ylcarbonyl, 1, 5-diazocan-2-ylcarbonyl and 1,5-diazocan-3-ylcarbonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “carboxy (group) that can be esterified” include carboxy,alkoxy-carbonyl which can be substituted, C₆₋₁₄ aryloxy-carbonyl whichcan be substituted, C₇₋₁₆ aralkyloxy-carbonyl which can be substituted,silyloxy-carbonyl which can be substituted (e.g., TMS-O—CO—, TES-O—CO—,TBS-O—CO—, TIPS-O—CO—, TBDPS-O—CO—, etc.)

Unless otherwise specifically stated, in this specification, examples ofthe “alkoxy-carbonyl (group)” include methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, and tert-butoxycarbonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryloxy-carbonyl (group)” include phenoxycarbonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₇₋₁₆ aralkyl-carbonyl (group)” include benzyloxycarbonyl andphenethyloxycarbonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “alkylsulfonyl (group)” include C₁₋₁₀ alkylsulfonyl (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkylsulfonyl (group)” include methylsulfonyl andethylsulfonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkylsulfonyl (group)” include cyclopropylsulfonyl,cyclobutylsulfonyl, cyclopentylsulfonyl and cyclohexylsulfonyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ arylsulfonyl (group)” include phenylsulfonyl,1-naphthylsulfonyl and 2-naphthylsulfonyl.

Unless otherwise specifically stated, in this specification, examples ofthe heterocyclic moiety of the “heterocyclic-sulfonyl (group)” includethose similar to said “heterocyclic group”. Specifically, examples ofthe “heterocyclic-sulfonyl (group)” include 5- to 14-memberedheterocyclic-sulfonyl (group) having 1 to 5 hetero atoms selected fromnitrogen, sulfur and oxygen

Unless otherwise specifically stated, in this specification, examples ofthe saturated heterocyclic moiety of the “saturatedheterocyclic-sulfonyl (group)” include those similar to said“heterocyclic group”. Specifically, examples of the“heterocyclic-sulfonyl (group)” include 5- to 14-memberedheterocyclic-sulfonyl (group) having 1 to 5 hetero atoms selected fromnitrogen, sulfur and oxygen.

Unless otherwise specifically stated, in this specification, examples ofthe “alkylsulfinyl (group)” include C₁₋₁₀ alkylsulfinyl (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkylsulfinyl (group)” include methylsulfinyl andethylsulfinyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkylsulfinyl (group)” include cyclopropylsulfinyl,cyclobutylsulfinyl, cyclopentylsufinyl, and cyclohexysulfinyl.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ arylsulfinyl (group)” include phenylsulfinyl,1-naphthylsulfinyl and 2-naphthylsulfinyl.

Unless otherwise specifically stated, in this specification, examples ofthe heterocyclic moiety of the “heterocyclic-sulfinyl (group)” includethose similar to said “heterocyclic group”. Specifically, examples ofthe “heterocyclic-sulfinyl (group)” include 5- to 14-memberedheterocyclic-sulfinyl (group) having 1 to 5 hetero atoms selected fromnitrogen, sulfur and oxygen.

Unless otherwise specifically stated, in this specification, examples ofthe “alkyl-carbamoyl (group)” include C₁₋₁₀ alkyl-carbamoyl (group).

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkyl-carbamoyl (group)” include methylcarbamoyl,ethylcarbamoyl and propylcarbamoyl.

Unless otherwise specifically stated, in this specification, examples ofthe “mono- or di-alkylamino (group)” include mono- or di-C₁₋₁₀alkylamino (group).

Unless otherwise specifically stated, in this specification, examples ofthe “mono- or di-C₁₋₁₀ alkylamino (group)” include methylamino,ethylamino, propylamino, dimethylamino and diethylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “alkyl-carbonylamino (group)” include C₁₋₁₀alkyl-carbonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe C₁₋₁₀ alkyl-carbonylamino (group)” include acetylamino,propionylamino and pivaloylamino.

Unless otherwise specifically stated, in this specification, examples ofthe heterocyclic moiety of the “heterocyclic-amino (group)” thosesimilar to said “heterocyclic group”. Examples of the“heterocyclic-amino (group)” include 2-pyridyl-amino.

Unless otherwise specifically stated, in this specification, examples ofthe “heterocyclic-carbonyl” of the “heterocyclic-carbonylamino (group)”those similar to said “heterocyclic-carbonyl”. Examples of the“heterocyclic-carbonylamino (group)” include pyridyl-carbonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “heterocyclic (group)” of the “heterocyclic-oxycarbonylamino(group)” include those similar to said “heterocyclic group”. Examples ofthe “heterocyclic-oxycarbonylamino (group)” include2-pyridyl-oxycarbonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “heterocyclic (group)” of the “heterocyclic-sulfonylamino (group)”include those similar to said “heterocyclic group”. Examples of the“heterocyclic-sulfonylamino (group)” include 2-pyridyl-sulfonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “alkoxy-carbonylamino (group)” include C₁₋₁₀alkoxy-carbonylamino.

Unless otherwise specifically stated, in this specification, the C₁₋₁₀alkoxy-carbonylamino (group)” include methoxycarbonylamino,ethoxycarbonylamino, propoxycarbonylamino and butoxycarbonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “alkyl-sulfonylamino (group)” include C₁₋₁₀alkyl-sulfonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “C₁₋₁₀ alkyl-sulfonylamino (group)” include methylsulfonylamino andethylsulfonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “mono- or di-C₃₋₇ cycloalkylamino (group)” include cyclopropylamino,cyclopentylamino and cyclohexylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyl-carbonylamino (group)” includecyclopropylcarbonylamino, cyclopentylcarbonylamino andcyclohexylcarbonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyloxy-carbonylamino (group)” includecyclopropoxycarbonylamino, cyclopentyloxycarbonylamino andcyclohexyloxycarbonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “C₃₋₇ cycloalkyl-sulfonylamino (group)” include cyclopropylsulfonylamino, cyclopentyl sulfonylamino and cyclohexyl sulfonylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “mono- or di-C₆₋₁₄ arylamino (group)” include phenylamino anddiphenylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “mono- or di-C₇₋₁₆ aralkylamino (group)” include benzylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryl-carbonylamino (group)” include benzoylamino andnaphthoylamino.

Unless otherwise specifically stated, in this specification, examples ofthe “C₆₋₁₄ aryl-sulfonylamino (group)” include phenylsulfonylamino,2-naphthylsulfonylamino and 1-naphthylsulfonylamino.

Symbols in the aforementioned formulas (Formula (I_(o)) and Formula (I))will be explained below.

In the aforementioned formula, R¹ represents a substituent.

Examples of the substituent represented by R¹ include substituentsselected from the below described substituent group A.

[Substituent Group A]

(1) a halogen atoms;

(2) a nitro group;

(3) a cyano group;

(4) a carboxy group that can be esterified;

(5) an alkyl group which can be substituted;

(6) an alkenyl group which can be substituted;

(7) an alkynyl group which can be substituted (e.g., an C₃₋₇cycloalkyl-C₂₋₆ alkynyl group which can be substituted;

(8) a C₃₋₇ cycloalkyl group which can be substituted;

(9) a C₆₋₁₄ aryl group which can be substituted;

(10) a C₇₋₁₆ aralkyl group which can be substituted;

(11) a C₆₋₁₄ aryl-C₂₋₆ alkenyl group which can be substituted;

(12) a heterocyclic group which can be substituted;

(13) a hydroxy group;

(14) an alkoxy group which can be substituted;

(15) a C₃₋₇ cycloalkyloxy group which can be substituted;

(16) a C₆₋₁₄ aryloxy group which can be substituted;

(17) a C₇₋₁₆ aralkyloxy group which can be substituted;

(18) an alkyl-carbonyloxy group which can be substituted;

(19) an alkoxy-carbonyloxy group which can be substituted;

(20) a mono-alkyl-carbamoyloxy group which can be substituted;

(21) a di-alkyl-carbamoyloxy group which can be substituted;

(22) a C₆₋₁₄ aryl-carbonyloxy group which can be substituted;

(23) a mono- or di-C₆₋₁₄ aryl-carbamoyloxy group which can besubstituted;

(24) a heterocyclic-oxy group which can be substituted (e.g., aromaticheterocyclic-oxy group which can be substituted)

(25) a C₁₋₁₀ alkylsulfonyloxy (group)” which can be substituted (e.g.,halogeno C₁₋₁₀ alkylsulfonyloxy (group) which can be substituted);

(26) a mercapto group;

(27) an alkylsulfanyl group which can be substituted;

(28) a C₃₋₇ cycloalkylsulfanyl group which can be substituted;

(29) a C₆₋₁₄ arylsulfanyl group which can be substituted;

(30) a C₇₋₁₆ aralkylsulfanyl group which can be substituted;

(31) a heterocyclic-sulfanyl group which can be substituted;

(32) a formyl group;

(33) an alkyl-carbonyl group which can be substituted;

(34) a C₃₋₇ cycloalkylcarbonyl group which can be substituted;

(35) a C₆₋₁₄ arylcarbonyl group which can be substituted;

(36) a C₇₋₁₆ aralkylcarbonyl group which can be substituted;

(37) a heterocyclic-carbonyl group which can be substituted;

(38) an alkylsulfonyl group which can be substituted;

(39) a C₃₋₇ cycloalkylsulfonyl group which can be substituted;

(40) a C₆₋₁₄ arylsulfonyl group which can be substituted;

(41) a heterocyclic-sulfonyl group which can be substituted;

(42) an alkylsulfinyl group which can be substituted;

(43) a C₃₋₇ cycloalkylsulfinyl group which can be substituted;

(44) a C₆₋₁₄ arylsulfinyl group which can be substituted;

(45) a heterocyclic-sulfinyl group which can be substituted;

(46) a sulfo group;

(47) a sulfamoyl group;

(48) a sulfinamoyl group;

(49) a sulfenamoyl group;

(50) a thiocarbamoyl group:

(51) a carbamoyl group which can be substituted [e.g., alkyl-carbamoylgroup which can be substituted]

(52) an amino group which can be substituted [e.g.,

amino,

mono- or di-alkylamino group which can be substituted,

mono- or di-C₃₋₇ cycloalkylamino group which can be substituted,

mono- or di-C₆₋₁₄ arylamino group which can be substituted,

mono- or di-C₇₋₁₆ aralkylamino group which can be substituted,

heterocyclic amino group which can be substituted,

C₆₋₁₄ aryl-carbonylamino group which can be substituted,

formylamino,

alkyl-carbonylamino group which can be substituted (e.g., mono-(C₁₋₁₀alkyl-carbonyl)-amino group which can be substituted),

C₃₋₇ cycloalkyl-carbonylamino group which can be substituted,

heterocyclic-carbonylamino group which can be substituted,

C₃₋₇ cycloalkyloxy-carbonylamino group which can be substituted,

heterocyclic-oxycarbonylamino group which can be substituted,

carbamoylamino group which can be substituted,

alkylsulfonylamino group which can be substituted,

C₃₋₇ cycloalkyl-sulfonylamino group which can be substituted,

heterocyclic sulfonylamino group which can be substituted,

C₆₋₁₄ arylsulfonylamino group which can be substituted]

Among the aforementioned substituent group A, i.e., particularly,

the “alkoxy-carbonyl group which can be substituted”,

the “alkyl group which can be substituted”,

the “alkenyl group which can be substituted”,

the “alkynyl group which can be substituted”,

the “alkoxy group which can be substituted”,

the “alkyl-carbonyloxy group which can be substituted”,

the “alkoxy-carbonyloxy group which can be substituted”,

the “mono-alkyl-carbamoyloxy group which can be substituted”,

the “dialkyl-carbamoyloxy group which can be substituted”,

the “alkylsulfanyl group which can be substituted”,

the “alkylcarbonyl group which can be substituted”,

the “alkylsulfonyl group which can be substituted”,

the “alkylsulfinyl group which can be substituted”,

the “alkyl-carbamoyl group which can be substituted”,

the “mono- or di-alkylamino group which can be substituted”,

the “alkyl-carbonylamino group which can be substituted”,

the “mono-(C₁₋₁₀ alkyl-carbonyl)-amino group which can be substituted”

the “alkoxy-carbonylamino group which can be substituted”, and

the “alkylsulfonylamino group which can be substituted”,

substituents thereof may be selected from, for example, the followingsubstituent group B. The number of the substituents ranges from 1 to themaximum number which can be substituted, more preferably from 1 to 3 andfurther preferably 1.

[Substituent Group B]

Substituent group B consists of

(a) a halogen atom;

(b) a hydroxy group;

(c) a nitro group;

(d) a cyano group;

(e) a C₆₋₁₄ aryl group which can be substituted (the “C₆₋₁₄ aryl group”can be substituted with one or more substituents selected from halogen,hydroxy, cyano, amino, C₁₋₁₀ alkyl that can be halogenated, mono- ordi-C₁₋₁₀ alkylamino, mono- or di-C₆₋₁₄ arylamino, mono- or di-C₇₋₁₆aralkylamino, C₃₋₇ cycloalkyl, C₁₋₁₀ alkoxy, formyl, C₁₋₁₀alkyl-carbonyl, C₃₋₇ cycloalkyl-carbonyl, C₆₋₁₄ aryl-carbonyl, C₇₋₁₆aralkyl-carbonyl, C₁₋₁₀alkoxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆aralkyloxy-carbonyl, C₁₋₁₀ alkylsulfanyl, C₁₋₁₀ alkylsulfinyl, C₁₋₁₀alkylsulfonyl, carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀alkylcarbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl and so on);

(f) a C₆₋₁₄ aryloxy group which can be substituted (the “C₆₋₁₄ aryloxygroup” can be substituted with one or more substituents selected fromhalogen, hydroxy, cyano, amino, C₁₋₁₀ alkyl that can be halogenated,mono- or di-C₁₋₁₀ alkylamino, mono- or di-C₆₋₁₄ arylamino, mono- ordi-C₇₋₁₆ aralkylamino, C₃₋₇ cycloalkyl, C₁₋₁₀ alkoxy, formyl,C₁₋₁₀alkyl-carbonyl, C₃₋₇ cycloalkyl-carbonyl, C₆₋₁₄ aryl-carbonyl,C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀alkoxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl,C₇₋₁₆ aralkyloxy-carbonyl, C₁₋₁₀ alkylsulfanyl, C₁₋₁₀ alkylsulfinyl,C₁₋₁₀ alkylsulfonyl, carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀alkylcarbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl and so on);

(g) a C₇₋₁₆ aralkyloxy group which can be substituted (the “C₇₋₁₆aralkyloxy group” can be substituted with one or more substituentsselected from halogen atoms, hydroxy, cyano, amino, C₁₋₁₀ alkyl that canbe halogenated, mono- or di-C₁₋₁₀ alkylamino, mono- or di-C₆₋₁₄arylamino, mono- or di-C₇₋₁₆ aralkylamino, C₃₋₇ cycloalkyl, C₁₋₁₀alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl, C₃₋₇ cycloalkyl-carbonyl, C₆₋₁₄aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀ alkoxy-carbonyl, C₆₋₁₄aryloxy-carbonyl, C₇₋₁₆ aralkyloxy-carbonyl, C₁₋₁₀ alkylsulfanyl, C₁₋₁₀alkylsulfinyl, C₁₋₁₀ alkylsulfonyl, carbamoyl, thiocarbamoyl, mono- ordi-C₁₋₁₀ alkylcarbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl and so on);

(h) a mono- or di-5- to 10-membered heterocyclic group having 1 to 4hetero atoms selected from nitrogen, sulfur and oxygen (e.g., furyl,pyridyl, thienyl, pyrrolidino, 1-piperidinyl, 4-piperidyl, piperazinyl,1-morpholinyl, 4-thiomorpholinyl, azepan-1-yl, azocan-1-yl, azonan-1-yl,3,4-dihydroisoquinoline-2-yl and the like) which can be substituted (the“mono- or di-5- to 10-membered heterocyclic group having 1 to 4 heteroatoms selected from nitrogen, sulfur and oxygen” can be substituted withone or more substituents selected from halogen, hydroxy, cyano, amino,C₁₋₁₀ alkyl that can be halogenated, mono- or di-C₁₋₁₀ alkylamino, mono-or di-C₆₋₁₄ arylamino, mono- or di-C₇₋₁₆ aralkylamino, C₃₋₇ cycloalkyl,C₁₋₁₀ alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl, C₃₋₇ cycloalkyl-carbonyl,C₆₋₁₄ aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀ alkoxy-carbonyl,C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆ aralkyloxy-carbonyl, C₁₋₁₀ alkylsulfanyl,C₁₋₁₀ alkylsulfinyl, C₁₋₁₀ alkylsulfonyl, carbamoyl, thiocarbamoyl,mono- or di-C₁₋₁₀ alkylcarbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl groupand so on);

(i) an amino group which can be substituted [e.g., Amino group which canbe substituted by one or two substituents selected from the groupconsisting of C₁₋₁₀ alkyl, C₂₋₆ alkenyl, C₆₋₁₄ aryl, C₇₋₁₆ aralkyl,heterocyclic group and heterocyclic-alkyl group (The C₁₋₁₀ alkyl, C₂₋₆alkenyl, C₆₋₁₄ aryl, C₇₋₁₆ aralkyl, heterocyclic group andheterocyclic-alkyl group can be substituted with halogen atoms, hydroxy,cyano, amino, C₁₋₁₀alkyl that can be halogenated (not the alkyl andalkenyl substituents), mono- or di-C₁₋₁₀ alkylamino, mono- or di-C₆₋₁₄arylamino, mono- or di-C₇₋₁₆ aralkylamino, C₃₋₇ cycloalkyl, C₁₋₁₀alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl, C₃₋₇ cycloalkyl-carbonyl, C₆₋₁₄aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀ alkoxy-carbonyl, C₃₋₇cycloalkyloxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆aralkyloxy-carbonyl, C₁₋₁₀ alkylsulfanyl, C₃₋₇ cycloalkylsulfanyl, C₁₋₁₀alkylsulfinyl, C₃₋₇ cycloalkylsulfinyl, C₁₋₁₀ alkylsulfonyl, C₃₋₇cycloalkylsulfonyl, carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀alkylcarbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl group). “Heterocyclic”and “heterocyclic” in “heterocyclic-alkyl” are the same as theaforementioned “heterocyclic group”];

(j) a C₃₋₇ cycloalkyl;

(k) a C₁₋₁₀ alkoxy which can be substituted (the “C₁₋₁₀ alkoxy” can besubstituted with one or more substituents selected from halogen,hydroxy, amino, mono- or di-C₁₋₁₀alkylamino, mono- or di-C₆₋₁₄arylamino, C₃₋₇ cycloalkyl, C₁₋₁₀ alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl,C₃₋₇ cycloalkyl-carbonyl, C₆₋₁₄ aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl,C₁₋₁₀ alkoxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆aralkyloxy-carbonyl, C₁₋₁₀ alkylsulfanyl, C₁₋₁₀ alkylsulfinyl, C₁₋₁₀alkylsulfonyl, carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀alkylcarbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl, and so on);

(l) a formyl;

(m) a C₁₋₁₀ alkyl-carbonyl (e.g., acetyl);

(n) a C₃₋₇ cycloalkyl-carbonyl;

(o) a C₆₋₁₄ aryl-carbonyl;

(p) a C₇₋₁₆ aralkyl-carbonyl;

(q) a C₁₋₁₀alkoxy-carbonyl;

(r) a C₆₋₁₄ aryloxy-carbonyl;

(s) a C₇₋₁₆ aralkyloxy-carbonyl;

(t) a C₁₋₁₀ alkylsulfanyl;

(u) a C₁₋₁₀ alkylsulfinyl;

(v) a C₁₋₁₀ alkylsulfonyl;

(w) a carbamoyl;

(x) a thiocarbamoyl;

(y) a mono-C₁₋₁₀ alkylcarbamoyl (e.g., methylcarbamoyl, ethylcarbamoyl,etc.);

(z) a di-C₁₋₁₀ alkylcarbamoyl (e.g., dimethylcarbamoyl,diethylcarbamoyl, ethylmethylcarbamoyl, etc.);

(aa) a mono- or di-C₆₋₁₄ aryl-carbamoyl (e.g., phenylcarbamoyl,1-naphthylcarbamoyl, 2-naphthylcarbamoyl, etc.); and

(bb) a mono- or di-5- to 7-membered heterocyclic-carbamoyl having 1 to 4hetero atoms selected from nitrogen, sulfur and oxygen (e.g.,2-pyridylcarbamoyl, 3-pyridylcarbamoyl, 4-pyridylcarbamoyl,2-thienylcarbamoyl, 3-thienylcarbamoyl, etc.).

Among the aforementioned substituent group A, i.e., particularly,

the “C₆₋₁₄ aryloxy-carbonyl which can be substituted”,

the “C₇₋₁₆ aralkyloxy-carbonyl which can be substituted”,

the “C₃₋₇ cycloalkyl-C₂₋₆ alkynyl which can be substituted”,

the “C₃₋₇ cycloalkyl which can be substituted”,

the “C₆₋₁₄ aryl which can be substituted”,

the “C₇₋₁₆ aralkyl which can be substituted”,

the “C₆₋₁₄ aryl-C₂₋₆ alkenyl which can be substituted”,

the “heterocyclic group which can be substituted”,

the “C₃₋₇ cycloalkyloxy which can be substituted”,

the “C₆₋₁₄ aryloxy which can be substituted”,

the “C₇₋₁₆ aralkyloxy which can be substituted”,

the “C₆₋₁₄ aryl-carbonyloxy which can be substituted”,

the “mono- or di-C₆₋₁₄ aryl-carbamoyloxy which can be substituted”,

the “heterocyclic-oxy which can be substituted”,

the “aromatic heterocyclic-oxy which can be substituted”,

the “C₃₋₇ cycloalkylsulfanyl which can be substituted”,

the “C₆₋₁₄ arylsulfanyl which can be substituted”,

the “C₇₋₁₆ aralkylsulfanyl which can be substituted”,

the “heterocyclic-sulfanyl which can be substituted”,

the “C₃₋₇ cycloalkyl-carbonyl which can be substituted”,

the “C₆₋₁₄ aryl-carbonyl which can be substituted”,

the “C₇₋₁₆ aralkyl-carbonyl which can be substituted”,

the “heterocyclic-carbonyl which can be substituted”,

the “C₃₋₇ cycloalkylsulfonyl which can be substituted”,

the “C₆₋₁₄ arylsulfonyl which can be substituted”,

the “heterocyclic-sulfonyl which can be substituted”,

the “C₃₋₇ cycloalkylsulfinyl which can be substituted”,

the “C₆₋₁₄ arylsulfinyl which can be substituted”,

the “heterocyclic-sulfinyl which can be substituted”,

the “carbamoyl group which can be substituted”,

the “amino group which can be substituted”,

the “mono- or di-C₃₋₇ cycloalkylamino group which can be substituted,

the “mono- or di-C₆₋₁₄ arylamino group which can be substituted,

the “mono- or di-C₇₁₆ aralkylamino group which can be substituted,

the “heterocyclic amino group which can be substituted,

the “C₆₋₁₄ aryl-carbonylamino group which can be substituted,

the “C₃₋₇ cycloalkyl-carbonylamino group which can be substituted,

the “heterocyclic-carbonylamino group which can be substituted,

the “C₃₋₇ cycloalkyloxy-carbonylamino group which can be substituted,

the “heterocyclic-oxycarbonylamino group which can be substituted,

the “carbamoylamino group which can be substituted,

the “alkylsulfonylamino group which can be substituted,

the “C₃₋₇ cycloalkyl-sulfonylamino group which can be substituted,

the “heterocyclic sulfonylamino group which can be substituted, and

the “C₆₋₁₄ arylsulfonylamino group which can be substituted,

substituents thereof may be selected from, for example, theaforementioned substituent group B and the following substituent groupB′. The number of substituents ranges from 1 to the maximum number whichcan be substituted, more preferably from 1 to 3 substituents and furtherpreferably 1 substituent.

[Substituent Group B′]

Substituent group B′ consists of

(a) C₁₋₁₀ alkyl, which can be substituted by one or more substituentsselected from halogen, hydroxy, cyano, amino, mono- or di-C₁₋₁₀alkylamino, mono- or di-C₆₋₁₄ arylamino, mono- or di-C₇₁₆ aralkylamino,C₃₋₇ cycloalkyl, C₁₋₁₀ alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl, C₃₋₇cycloalkyl-carbonyl, C₆₋₁₄ aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀alkoxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆ aralkyloxy-carbonyl,C₁₋₁₀ alkylsulfanyl, C₁₋₁₀ alkylsulfinyl, C₁₋₁₀ alkylsulfonyl,carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀alkylcarbamoyl, mono- ordi-C₆₋₁₄ aryl-carbamoyl, and so on;

(b) C₂₋₆ alkenyl, which can be substituted by one or more substituentsselected from halogen, hydroxy, cyano, amino, mono- or di-C₁₋₁₀alkylamino, mono- or di-C₆₋₁₄ arylamino, mono- or di-C₇₁₆ aralkylamino,C₃₋₇ cycloalkyl, C₁₋₁₀ alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl, C₃₋₇cycloalkyl-carbonyl, C₆₋₁₄ aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀alkoxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆ aralkyloxy-carbonyl,C₁₋₁₀ alkylsulfanyl, C₁₋₁₀ alkylsulfinyl, C₁₋₁₀ alkylsulfonyl,carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀ alkylcarbamoyl, mono- ordi-C₆₋₁₄ aryl-carbamoyl, and so on; and

(c) C₂₋₆ alkynyl, which can be substituted by one or more substituentsselected from halogen atoms, hydroxy, cyano, amino, mono- or di-C₁₋₁₀alkylamino, mono- or di-C₆₋₁₄ arylamino, mono- or di-C₇₁₆ aralkylamino,C₃₋₇ cycloalkyl, C₁₋₁₀ alkoxy, formyl, C₁₋₁₀ alkyl-carbonyl, C₃₋₇cycloalkyl-carbonyl, C₆₋₁₄ aryl-carbonyl, C₇₋₁₆ aralkyl-carbonyl, C₁₋₁₀alkoxy-carbonyl, C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₆ aralkyloxy-carbonyl,C₁₋₁₀ alkylsulfanyl, C₁₋₁₀ alkylsulfinyl, C₁₋₁₀ alkylsulfonyl,carbamoyl, thiocarbamoyl, mono- or di-C₁₋₁₀ alkylcarbamoyl, mono- ordi-C₆₋₁₄ aryl-carbamoyl group, and so on.

Among them, R¹ is, for example, preferably

an alkyl group which can be substituted,

a C₃₋₇ cycloalkyl group which can be substituted,

a C₆₋₁₄ aryl group which can be substituted,

a non-aromatic heterocyclic group which can be substituted, or

a heterocyclic group which can be substituted.

Among them, specifically, R¹ is, for example,

preferably a phenyl group which can be substituted by 1 to 5substituents selected from a halogen atom, a C₁₋₁₀ alkyl group which canbe substituted, a C₁₋₁₀alkoxy group which can be substituted,

more preferably a phenyl group which can be substituted by 1 to 5substituents selected from a halogen atom, a C₁₋₁₀ alkyl group, and aC₁₋₁₀ alkoxy group, and

further preferably a phenyl group which can be substituted by 1 to 5halogen atoms.

In another aspect of the present invention, as R¹, in particular, forexample,

a 5- or 6-membered aromatic group (preferably phenyl group, pyridylgroup) which can be substituted by one or more substituents selectedfrom

a halogen atom (preferably, a chlorine atom, a fluorine atom),

a cyano group,

a hydroxy group,

an alkyl group (preferably, methyl group, isobutyl group) which can besubstituted,

an alkoxy group (preferably methoxy group) which can be substituted,

an alkylsulfanyl group which can be substituted,

an alkylsulfinyl group which can be substituted,

an alkylsulfonyl group which can be substituted, and

an amino group which can be substituted

are preferable.

The number of substituents ranges from 1 to the maximum number which canbe substituted, more preferably from 1 to 3 substituents and furtherpreferably 1 substituent.

In particular, for example, aromatic group which can be substituted aredesirable as R¹. The “aromatic group which can be substituted” include“C₆₋₁₄ aryl which can be substituted” and “heteroaryl which can besubstituted” among the substituents listed above.

R¹ is, for example, preferably a phenyl group which is substituted byone or more (preferably, 1 to 5) substituents selected from

(a) C₁₋₁₀ alkyl group (e.g., isopropyl, isobutyl), and

(b) halogen atoms (e.g., chlorine, fluorine), C₁₋₁₀ alkyl group (e.g.,methyl), C₁₋₁₀ alkoxy group (e.g., methoxy).

In the aforementioned formula, R² represents a hydrogen atom or asubstituent.

Examples of the substituent represented by R² include substituentsselected from the aforementioned substituent group A.

Among them, R² is, for example, preferably

a halogen atom,

a hydroxy group,

an alkyl group which can be substituted, or

an alkoxy group which can be substituted.

Among them, specifically, R² is, for example,

preferably a halogen atom, a hydroxy group, a C₁₋₁₀ alkyl group whichcan be substituted, or a C₁₋₁₀ alkoxy group which can be substituted,

more preferably a C₁₋₁₀ alkoxy group which can be substituted by one ormore substituents selected from a halogen atom, a C₁₋₁₀ alkoxy group,and a C₃₋₇ cycloalkyl group, and

further preferably a C₁₋₁₀ alkoxy group.

In another aspect of the present invention, as R², in particular, forexample,

(i) a hydrogen atom,

(ii) a halogen atom,

(iii) a hydroxy group,

(iv) an alkyl group which can be substituted by one or more substituentsselected from halogen atoms, hydroxy group, amino group, and alkoxygroup,

(v) an amino group that can be mono- or di-substituted with alkyl group,or

(vi) an alkoxy group which can be substituted by one or moresubstituents selected from cyano group, amino group, alkoxy group,hydroxy group, halogen atoms and C₃₋₇ cycloalkyl group

is preferable, and, for example,

(i) a hydrogen atom,

(ii) a hydroxy group,

(iii) a C₁₋₁₀ alkyl group (e.g., methyl), or

(iv) a C₁₋₁₀ alkoxy group (e.g., methoxy, ethoxy, isopropoxy,cyclopropylmethoxy, difluoromethoxy) which can be substituted by one ormore substituents selected from halogen atoms and C₃₋₇ cycloalkyl group

is more preferable.

In the aforementioned formula, R³ represents a hydrogen atom or asubstituent.

Examples of the substituents represented by R³ include substituentsselected from the aforementioned substituent group A.

Among them, R³ is, for example, preferably

a halogen atom,

a hydroxy group,

an alkyl group which can be substituted, or

an alkoxy group which can be substituted.

Among them, specifically, R³ is, for example,

preferably a hydrogen atom, or a C₁₋₁₀ alkoxy group which can besubstituted,

more preferably a hydrogen atom, or a C₁₋₁₀ alkoxy group, and

further preferably a hydrogen atom.

In another aspect of the present invention, as R³, in particular, forexample,

(i) hydrogen atom,

(ii) halogen atoms,

(iii) alkyl group which can be substituted by one or more substituentsselected from halogen atoms, hydroxy group, amino group, and alkoxygroup,

(iv) amino group that can be mono- or di-substituted with alkyl group,or

(vi) alkoxy group, and for example,

is preferable, and, for example,

a hydrogen atom and a C₁₋₁₀ alkyl group (e.g., methyl)

is more preferable.

In the aforementioned formula, Ring A represents an aromatic ring whichcan be substituted.

The “aromatic ring” of the “aromatic ring which can be substituted” ispreferably a 5 to 16-membered aromatic ring, more preferably a 5 to6-membered aromatic ring, and further preferably a 6-membered aromaticring.

The “aromatic ring” of the “aromatic ring which can be substituted”represented by the ring A, for example, includes (i) an aromatic cyclichydrocarbon, (ii) an aromatic heterocyclic ring containing 1 to 4heteroatoms selected from nitrogen, oxygen and sulfur.

Said “(i) aromatic cyclic hydrocarbon, for example, includes C₆₋₁₄aromatic cyclic hydrocarbons such as benzene, naphthalene, anthracene,phenanthrene, acenaphthylene (preferably C₆₋₁₂ aromatic cyclichydrocarbons, particularly benzene is preferable).

Said “(ii) aromatic heterocyclic ring containing 1 to 4 hetero atomsselected from nitrogen, oxygen, and sulfur, for example, includes 5- or6-membered aromatic monocyclic type heterocyclic rings such as furan,thiophene, pyrrole, 1, 3-oxazole, isoxazole, 1, 3-thiazole, isothiazole,imidazole, pyrazole, 1, 2, 3-oxadiazole, 1, 2, 4-oxadiazole, 1, 3,4-oxadiazole, furazan, 1, 2, 3-thiadiazole, 1, 2, 4-thiadiazole, 1, 3,4-thiadiazole, 1, 2, 3-triazole, 1, 2, 4-triazole, tetrazole, pyridine,pyridazine, pyrimidine, pyrazine, 1, 2, 3-triazine, 1, 3, 5-triazine, 1,2, 4-triazine, 1, 2, 3, 4-tetrazine, 1, 2, 3, 5-tetrazine, 1, 2, 4,5-tetrazine and the like; and

8 to 16-membered (preferably 8 to 12-membered) aromatic condensedheterocyclic rings (preferably heterocyclic rings formed by condensationof 1 to 2 said 5- to 6-membered aromatic monocyclic heterocyclic rings(preferably 1 ring) with 1 to 2 benzene rings (preferably 1 ring), orheterocyclic rings formed by condensation of 2 to 3 said identical 5- to6-membered aromatic monocyclic heterocyclic rings or differentheterocyclic rings) such as benzofuran, isobenzofuran, benzothiophene,indole, isoindole, 1H-indazole, benzimidazole, benzoxazole,benzisoxazole, benzothiazole, benzisothiazole, 1H-benzotriazole,quinoline, isoquinoline, cinnoline, quinazoline, quinoxaline,phthalazine, naphthyridine, purine, pteridine, carbazole, α-carboline,β-carboline, γ-carboline, acridine, phenoxazine, phenothiazine,phenazine, phenoxathiin, thianthrene, phenanthridine, phenanthroline,indolizine, pyrrolopyridine, pyrrolo[1,2-b]pyridazine,

1H-pyrrolo[2, 3-b]pyrazine, pyrazolo[1,5-a] pyridine,imidazo[1,2-a]pyridine, imidazo[1,2-b]pyridazine,imidazo[1,2-a]pyrimidine, 1, 2, 4-triazolo[4,3-a]pyridine, 1, 2,4-triazolo[4,3-b]pyridazine and the like).

When the “(ii) aromatic heterocyclic ring containing 1 to 4 hetero atomsselected from nitrogen, oxygen, and sulfur contains nitrogen, thearomatic heterocyclic ring can form an N-oxide.

Among them, preferred is benzene, pyridine, pyridazine, pyrimidine,pyrazine, pyridine N-oxide, 1, 2, 3-triazine, 1, 3, 5-triazine, 1, 2,4-triazine, 1, 2, 3, 4-tetrazine, 1, 2, 3, 5-tetrazine, 1, 2, 4,5-tetrazine, pyrrole, furan, thiophene, pyrazole, imidazole, isoxazole,isothiazole, 1, 3-oxazole, 1, 3-thiazole, 1, 2, 3-triazole, 1, 2,4-triazole, tetrazole, 1, 2, 3-oxadiazole, 1, 2, 3-thiadiazole,naphthalene, quinoline, quinazoline, quinoxaline, benzofuran,benzothiophene, benzoxazole, benzothiazole, benzimidazole, indole,1H-indazole, 1H-pyrrolo[2,3-b]pyrazine, 1H-pyrrolopyridine,1H-imidazopyridine, 1H-imidazopyrazine, triazine, isoquinoline,benzothiadiazole, benzisoxazole, benzisothiazole, indazole, purine,isoquinoline, phthalazine, naphthyridine, cinnoline, pteridine or thelike, especially preferred is, for example, benzene or pyridine, andmost preferred is benzene.

The substituents of the “aromatic ring which can be substituted” asrepresented by the ring A, for example, include the substituentsselected from the aforementioned substituent group A.

In particular, preferred examples of the substituents of the “aromaticring which can be substituted” include

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted,

(5) a C₁₋₁₀ alkylsulfonyl group which can be substituted,

(6) a C₃₋₇ cycloalkyl group which can be substituted,

(7) a cyano group,

(8) a carbamoyl group which can be substituted,

(9) a C₁₋₁₀ alkylsulfonyloxy group which can be substituted,

(10) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group which can be substituted,

(11) a tetrahydropyranyl group which can be substituted,

(12) a dihydropyranyl group which can be substituted,

(13) a mono-(C₁₋₁₀ alkyl-carbonyl)-amino group which can be substituted,

(14) a C₁₋₁₀ alkoxy-carbonyl group which can be substituted,

(15) a C₁₋₁₀ alkylsulfinyl group which can be substituted,

(16) a C₁₋₁₀ alkylsulfanyl group which can be substituted, and so on.

As it is apparent for a person of ordinary skill in the art, the “4- to6-membered heterocyclic group containing 0 or 1 oxygen atom, and 1 to 3nitrogen atoms as heteroatoms” of the “4- to 6-membered heterocyclicgroup containing 0 or 1 oxygen atom, and 1 to 3 nitrogen atoms asheteroatoms which can be substituted” is included in the “heterocyclicgroup” of the “heterocyclic group which can be substituted”.

The number of substituents preferably ranges from 1 to 5.

The number of the substituents of the “heterocyclic group which can besubstituted” is one or more, preferably in the range of 1 to 5, morepreferably in the range of 1 to 3, further preferably one or two.

When the number of the substituents is two or more, the substituents onthe Ring A can be combined to form a ring which can be substituted. The“ring” of the “ring which can be substituted” include a 5- to 6-memberedheterocyclic ring containing one nitrogen atom or two oxygen atoms asheteroatoms.

The “ring” can be substituted by one or more (preferably, 1 to 5)substituents selected from the Substituent group A.

In another aspect of the present invention, preferred examples of thesubstituents of the “aromatic ring which can be substituted” representedby Ring A include

a halogen atoms (preferably halogen atom)

a cyano group,

a hydroxy group,

an alkyl group which can be substituted (preferably C₁₋₁₀ alkyl groupwhich can be substituted by 1 to 3 halogen atoms [e.g., trifluoromethylgroup]),

a alkoxy group which can be substituted (preferably C₁₋₁₀ alkoxy groupwhich can be substituted by 1 to 3 halogen atoms [e.g., methoxy group,difluoromethoxy group]),

a carbamoyl group

a heterocyclic-oxy group (preferably 5- to 10-membered heterocyclic-oxygroup containing 1 to 3 hetero atoms selected from nitrogen, oxygen andsulfur [e.g., benzimidazolyloxy group]),

an alkylsulfanyl group which can be substituted,

an alkylsulfinyl group which can be substituted,

an alkylsulfonyl group which can be substituted (preferably C₁₋₁₀alkylsulfonyl group [e.g., methylsulfonyl group]),

a heterocyclic-sulfonyl group (preferably 5- to 6-membered saturatedheterocyclic-sulfonyl group containing 1 to 3 hetero atoms selected fromnitrogen, oxygen and sulfur [e.g., morpholinylsulfonyl group]),

an amino group which can be substituted,

a cycloalkyl group (preferably C₃₋₇ cycloalkyl [e.g., cyclohexyl]) andsaturated heterocyclic group (preferably 5- to 6-membered saturatedheterocyclic group containing 1 to 3 hetero atoms selected fromnitrogen, oxygen and sulfur [e.g., morpholinyl group and piperidylgroup]).

Ring A is, for example, preferably

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by oneor more substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted, and a C₁₋₁₀ alkyl group which can be substituted.

Ring A is, for example, more preferably

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom (1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted by 1 to 3 halogenatoms,

(3) a C₁₋₁₀ alkoxy group which can be substituted by 1 to 3 halogenatoms,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by 1to 4 substituents selected from a halogen atom, a hydroxy group, an oxogroup, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀alkoxy group which can besubstituted by halogen, and a C₁₋₁₀ alkyl group which can be substitutedby halogen.

Ring A is, for example, further preferably

a benzene ring which is substituted with

(1) (i) 1 or 2 halogen atoms, or (ii) one C₁₋₁₀ alkoxy group, and

(2) one 4- to 6-membered heterocyclic group containing 0 or 1 oxygenatom, and 1 to 3 nitrogen atoms as heteroatoms which can be substitutedby 1 to 4 substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted by halogen, and a C₁₋₁₀ alkyl group which can besubstituted by halogen.

Here, as the “one 4- to 6-membered heterocyclic group containing 0 or 1oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms”, for example,preferred is a morpholino group, a pyrrolyl group, a dihydropyrrolylgroup, a pyrazolyl group, a dihydropyrazolyl group, a piperidyl group,an azetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group or an imidazolidinyl group.

In another aspect of the present invention, as ring A, in particular,for example,

preferred is a 5- to 6-membered aromatic group which can be substitutedby one or more substituents selected from halogen atoms, cyano group,hydroxy group, alkyl group which can be substituted, alkoxy group whichcan be substituted, carbamoyl group, alkylsulfanyl group which can besubstituted, alkylsulfinyl group which can be substituted, alkylsulfonylgroup which can be substituted, heterocyclic-sulfonyl group, amino groupwhich can be substituted, cycloalkyl group, and saturated heterocyclicgroup, and

further specifically, preferred is a 5- to 6-membered aromatic group(e.g., phenyl, pyridyl) which can be substituted by one or moresubstituents selected from (a) a halogen atom (e.g., chlorine,fluorine),

(b) a Cyano group,

(c) a C₁₋₁₀ alkyl group which can be substituted by 1 to 3 halogen atoms(e.g., methyl, trifluoromethyl),

(d) a C₃₋₇ cycloalkyl group (e.g., methyl, trifluoromethyl),

(e) a C₁₋₁₀ alkoxy group which can be substituted by 1 to 3 halogenatoms (e.g., difluoromethoxy, methoxy),

(f) a 5- to 10-membered heterocyclic group containing 1 to 3 heteroatoms selected from nitrogen, oxygen and sulfur (e.g., morpholinyl,benzimidazolyl, piperidinyl),

(g) a C₁₋₁₀ alkyl-sulfonyl group (e.g., methylsulfonyl),

(h) a 5- to 10-membered heterocyclic-sulfonyl group containing 1 to 3hetero atoms selected from nitrogen, oxygen and sulfur (e.g.,morpholinylsulfonyl), and

(i) a carbamoyl group.

In the aforementioned formula, the ring B represents a “5-memberedaromatic heterocyclic ring which can be substituted”.

Examples of the “5-membered aromatic heterocyclic ring which can besubstituted” represented by the ring B include 5-membered aromaticheterocyclic rings containing 1 to 4 hetero atoms (preferably 1 to 2atoms) selected from nitrogen, oxygen and sulfur such as pyrrole, furan,thiophene, pyrazole, imidazole, isoxazole, isothiazole, 1,3-oxazole,1,3-thiazole, triazole (e.g., 1,2 3-triazole, 1,2,4-triazole),tetrazole, oxadiazole (e.g., 1,2 3-oxadiazole), and thiadiazole (e.g.,1,2,3-thiadiazole). Among them, pyrazole, triazole, and tetrazole arepreferable, and pyrazole is most preferable.

As the substituents of the “5-membered aromatic heterocyclic representedby the ring B, for example, the substituents selected from theaforementioned substituent group A can be included.

Preferable examples of the substituents include a halogen atom, an alkylgroup which can be substituted and a C₆₋₁₄ aryl group which can besubstituted, more preferable examples thereof include a halogen atom, analkyl group, and a C₆₋₁₄ aryl group, further preferable examples thereofinclude an alkyl group (e.g., methyl).

Also preferably, the ring B does not have such a substituent. In otherwords, the ring B has only substituents shown in the general formula of(I₀).

The ring B is preferably a 5-membered nitrogen-containing aromaticheterocyclic ring having 1 to 3 hetero atoms selected from nitrogen,oxygen and sulfur, which can be substituted by a C₁₋₁₀ alkyl group(e.g., methyl) (e.g., pyrazole, triazole, tetrazole).

As the Ring B, preferred is an imidazole ring, a pyrazole ring, atriazole ring or a tetrazole ring, each of which can be furthersubstituted with 1 to 3 substituents selected from a halogen atom, and aC₁₋₁₀ alkyl group which can be substituted by halogen, more preferred isa pyrazole ring which can be further substituted with 1 to 3substituents selected from a halogen atom, and a C₁₋₁₀ alkyl group whichcan be substituted by halogen, especially preferred is a pyrazole ring.

In another aspect of the present invention, the ring B is preferably a5-membered nitrogen-containing aromatic heterocyclic ring having 1 to 3nitrogen atoms (e.g., pyrazole, triazole, tetrazole), which can besubstituted by a C₁₋₁₀ alkyl group (e.g., methyl)

Further preferably, examples of the substituents, moieties and rings asexplained in the present specification are used in combination.

For example, the following compounds, i.e., compounds (I₀-A), (I₀-B),(I₀-C), (I₀-D), (I₀-E), (I₀-F), and (I₀-G) are preferable as a compound(I_(o)).

[Compound (I₀-A)]

The above described compound (I₀), wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 substituents selectedfrom a halogen atom, a C₁₋₁₀ alkyl group which can be substituted, and aC₁₋₁₀ alkoxy group which can be substituted,

R² represents

a halogen atom, a hydroxy group, a C₁₋₁₀ alkyl group which can besubstituted, or a C₁₋₁₀alkoxy group which can be substituted,

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group which can be substituted,

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted,

(5) a C₁₋₁₀ alkylsulfonyl group which can be substituted,

(6) a C₃₋₇ cycloalkyl group which can be substituted,

(7) a cyano group,

(8) a carbamoyl group which can be substituted,

(9) a C₁₋₁₀ alkylsulfonyloxy group which can be substituted,

(10) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group which can be substituted,

(11) a tetrahydropyranyl group which can be substituted,

(12) a dihydropyranyl group which can be substituted,

(13) a mono-(C₁₋₁₀alkyl-carbonyl)-amino group which can be substituted,

(14) a C₁₋₁₀alkoxy-carbonyl group which can be substituted,

(15) a C₁₋₁₀ alkylsulfinyl group which can be substituted, and

(16) a C₁₋₁₀ alkylsulfanyl group which can be substituted, and

Ring B represents

an imidazole ring, pyrazole ring, a triazole ring or a tetrazole ring,each of which can be further substituted with 1 to 3 substituentsselected from a halogen atom, and a C₁₋₁₀alkyl group which can besubstituted by halogen.

[Compound (I₀-B)]

The above described compound (I₀-A), wherein

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted,

(3) a C₁₋₁₀ alkoxy group which can be substituted,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by oneor more substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted, and a C₁₋₁₀ alkyl group which can be substituted.

[Compound (I₀-C)]

The above described compound (I₀), wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 substituents selectedfrom a halogen atom, a C₁₋₁₀ alkyl group, and a C₁₋₁₀ alkoxy group,

R² represents

a C₁₋₁₀ alkoxy group which can be substituted by one or moresubstituents selected from a halogen atom, a C₁₋₁₀ alkoxy group, and aC₃₋₇ cycloalkyl group,

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group,

Ring A represents

a benzene ring which can be substituted by 1 to 5 substituents selectedfrom

(1) a halogen atom,

(2) a C₁₋₁₀ alkyl group which can be substituted by 1 to 3 halogenatoms,

(3) a C₁₋₁₀ alkoxy group which can be substituted by 1 to 3 halogenatoms,

(4) a C₃₋₇ cycloalkyl group,

(5) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and

(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by 1to 4 substituents selected from a halogen atom, a hydroxy group, an oxogroup, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which can besubstituted by halogen, and a C₁₋₁₀ alkyl group which can be substitutedby halogen,

Ring B represents

a pyrazole ring which can be further substituted with 1 to 3substituents selected from a halogen atom, and a C₁₋₁₀ alkyl group whichcan be substituted by halogen.

[Compound (I₀-D)]

The above described compound (I₀), wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 halogen atoms,

R² represents

a C₁₋₁₀ alkoxy group,

R³ represents

a hydrogen atom,

Ring A represents

a benzene ring which is substituted with

(1) (i) 1 or 2 halogen atoms, or (ii) one C₁₋₁₀ alkoxy group, and

(2) one 4- to 6-membered heterocyclic group containing 0 or 1 oxygenatom, and 1 to 3 nitrogen atoms as heteroatoms which can be substitutedby 1 to 4 substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted by halogen, and a C₁₋₁₀ alkyl group which can besubstituted by halogen,

Ring B represents

a pyrazole ring.

Here, as the “one 4- to 6-membered heterocyclic group containing 0 or 1oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms”, for example,preferred is a morpholino group, a pyrrolyl group, a dihydropyrrolylgroup, a pyrazolyl group, a dihydropyrazolyl group, a piperidyl group,an azetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group or an imidazolidinyl group.

[Compound (I₀-E)]

The above described compound (I₀), wherein

R¹ represents

an aromatic group which can be substituted,

Ring A represents

an aromatic ring which is substituted with

(a) one substituent selected from

(1) a C₃₋₇ cycloalkyl group which can be substituted, and

(2) a 4- to 6-membered heterocyclic group containing 1 to 5 heteroatomsselected from a nitrogen atom, a sulfur atom, and an oxygen atom whichcan be substituted, and

(b) one or more further substituents.

Here, especially preferably, the further substituents are 1 to 4substituents selected from

(1) a halogen atom,

(2) an oxo group,

(3) a hydroxy group,

(4) a C₁₋₁₀ alkyl group which can be substituted,

(5) a C₁₋₁₀ alkoxy group which can be substituted,

(6) a C₁₋₁₀ alkylsulfonyl group,

(7) a morpholin-4-yl sulfonyl group,

(8) a cyano group,

(9) a carbamoyl group,

(10) a halogeno C₁₋₁₀ alkylsulfonyloxy group,

(11) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group,

(12) a di-C₁₋₁₀ alkyl-amino group,

(13) a mono-(C₁₋₁₀ alkyl-carbonyl)-amino group,

(14) a C₁₋₁₀ alkoxy-carbonyl group,

(15) a phenoxy group,

(16) a C₁₋₁₀ alkylsulfinyl group,

(17) a di-C₁₋₁₀ alkyl-amino group,

(18) a benzimidazole-2-yloxy group, and

(19) a benzimidazole-2-yl sulfonyl group.

[Compound (I₀-F)]

The above described compound (I₀-E), wherein

R¹ represents

a phenyl group which can be substituted,

R² represents

a hydrogen atom, a halogen atom, a hydroxy group, a C₁₋₁₀alkyl groupwhich can be substituted, or a C₁₋₁₀ alkoxy group which can besubstituted,

R³ represents

a hydrogen atom, or a C₁₋₁₀ alkoxy group which can be substituted,

Ring A represents

a benzene ring which

is substituted with one substituent selected from

(1) a C₃₋₇ cycloalkyl group which can be substituted,

(2) a dihydropyranyl group which can be substituted,

(3) a tetrahydropyranyl group which can be substituted, and

(4) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted,

and can be substituted by further substituents, and

Ring B represents

an imidazole ring, a pyrazole ring, a triazole ring, a tetrazole ring,an isoxazole ring, an 1,3-oxazole ring, a furan ring, or a thiophenering, each of which can be substituted.

Here, as the “one 4- to 6-membered heterocyclic group containing 0 or 1oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms”, for example,preferred is a morpholino group, a pyrrolyl group, a dihydropyrrolylgroup, a pyrazolyl group, a dihydropyrazolyl group, a piperidyl group,an azetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group, an imidazolidinyl group, an isoxazolyl group, apyridyl group, a piperazinyl group, or a thiazolyl group.

[Compound (I₀-G)]

The Compound (I₀-E), or the Compound (I₀-F), wherein

R¹ represents

a phenyl group which can be substituted by 1 to 5 halogen atoms,

R² represents

a hydrogen atom or a C₁₋₁₀ alkoxy group,

R³ represents

a hydrogen atom,

Ring A represents

a benzene ring,

which is substituted with one 4- to 6-membered heterocyclic groupcontaining 0 or 1 oxygen atom, and 1 to 3 nitrogen atoms as heteroatomswhich can be substituted by 1 to 4 substituents selected from a halogenatom, a hydroxy group, an oxo group, halogeno C₁₋₁₀ alkoxy group, aC₁₋₁₀ alkoxy-carbonyl, and a C₁₋₁₀ alkyl group which can be substitutedby halogen,

and which can be further substituted with 1 or 2 substituents selectedfrom a halogen atom and a C₁₋₁₀ alkoxy group, and

Ring B represents

a pyrazole ring.

Here, as the “one 4- to 6-membered heterocyclic group containing 0 or 1oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms”, for example,preferred is a morpholino group, a pyrrolyl group, a dihydropyrrolylgroup, a pyrazolyl group, a dihydropyrazolyl group, a piperidyl group,an azetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group or an imidazolidinyl group.

In another aspect of the present invention, the following compounds,i.e., compounds (I₀-H) and (I₀-I) are preferable as a compound (I_(o)).

[Compound (I₀-H)]

Compound (I₀), wherein

wherein

R¹ represents alkyl group which can be substituted, alkoxy group whichcan be substituted, cycloalkyl group which can be substituted, oraromatic group which can be substituted,

R² represents a hydrogen atom, a hydroxy group, alkyl group which can besubstituted, or alkoxy group which can be substituted,

R³ represents a hydrogen atom or alkyl group which can be substituted,

Ring A represents a 5- or 6-membered aromatic ring which can besubstituted by one or more substituents selected from halogen atoms,cyano group, hydroxy group, alkyl group which can be substituted, alkoxygroup which can be substituted, carbamoyl group, alkylsulfanyl groupwhich can be substituted, alkylsulfinyl group which can be substituted,heterocyclic-sulfonyl group, amino group which can be substituted,cycloalkyl group, and saturated heterocyclic group, and

Ring B represents a 5-membered aromatic heterocyclic ring which can besubstituted.

[Compound (I₀-I)]

Compound (I₀), wherein

Ring A is a 5- to 6-membered aromatic ring (e.g., phenyl pyridyl) whichcan be substituted by one or more substituents selected from

(a) halogen atoms (e.g., chlorine, fluorine, iodine)

(b) cyano group

(c) C₁₋₁₀ alkyl group which can be substituted by 1 to 3 halogen atoms(e.g., methyl, trifluoromethyl),

(d) C₃₋₇ cycloalkyl group (e.g., methyl, trifluoromethyl),

(e) C₁₋₁₀ alkoxy group which can be substituted by 1 to 3 halogen atoms(e.g., difluoromethoxy, methoxy),

(f) 5- to 10-membered heterocyclic group containing 1 to 3 hetero atomsselected from nitrogen, oxygen and sulfur (e.g., morpholinyl,benzimidazolyl, piperidinyl),

(g) C₁₋₁₀ alkyl-sulfonyl group (e.g., methylsulfonyl)

(h) 5- to 10-membered heterocyclic-sulfonyl group containing 1 to 3hetero atoms selected from nitrogen, oxygen and sulfur (e.g.,morpholinylsulfonyl),

(i) carbamoyl group,

R¹ represents

(a) C₁₋₁₀ alkyl group (e.g., isopropyl, isobutyl), or

(b) halogen atoms (e.g., chlorine, fluorine), C₁₋₁₀ alkyl group (e.g.,methyl) C₁₋₁₀ alkoxy group (e.g., methoxy),

R² represents

(a) hydrogen

(b) hydroxy group

(c) C₁₋₁₀ alkyl group (e.g., methyl), or

(d) C₁₋₁₀ alkoxy group which can be substituted by one or moresubstituents selected from halogen atoms and C₃₋₇ cycloalkyl group(e.g., methoxy, ethoxy, isopropoxy, cyclopropylmethoxy,difluoromethoxy),

R³ represents

hydrogen, or C₁₋₁₀ alkyl group (e.g., methyl),

the ring B is preferably a 5-membered nitrogen-containing aromaticheterocyclic ring having 1 to 3 nitrogen atoms (e.g., pyrazole,triazole, tetrazole), which can be substituted by a C₁₋₁₀ alkyl group(e.g., methyl)

Preferably, the compound (I_(o)) does not include the followingcompounds or salts thereof:

-   1-(2-chlorophenyl)-6-methyl-3-{5-thioxo-4-[3-(trifluoromethyl)phenyl]-4,5-dihydro-1H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-[4-(2-fluorophenyl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl]-6-methylpyridazin-4(1H)-one,-   1-(4-chlorophenyl)-6-methyl-3-{5-thioxo-4-[3-(trifluoromethyl)phenyl]-4,5-dihydro-1H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-[4-(2-fluorophenyl)-5-(methylsulfanyl)-4H-1,2,4-triazol-3-yl]-6-methylpyridazin-4(1H)-one,-   1-(4-chlorophenyl)-6-methyl-3-{5-(methyl    sulfanyl)-4-[3-(trifluoromethyl)phenyl]-4H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   1-(2-chlorophenyl)-6-methyl-3-{5-(methyl    sulfanyl)-4-[3-(trifluoromethyl)phenyl]-4H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,-   3-(3,5-dimethyl-1H-pyrazol-1-yl)-1-phenylpyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-{1-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]-1H-pyrazol-5-yl}pyridazin-4(1H)-one,-   3-[1-(2-fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-chlorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(4-methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-nitrophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(1,1-dioxidotetrahydrothiophen-3-yl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(4-methylphenyl)-1H-pyrazol-5-yl]-1-phenylpyridazin-4(1H)-one,-   3-[1-(4-chlorophenyl)-1H-pyrazol-5-yl]-1-phenylpyridazin-4(1H)-one,-   3-(4-ethyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-1-(4-methylphenyl)pyridazin-4(1H)-one,-   1-(4-chlorophenyl)-3-{1-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]-1H-pyrazol-3-yl}pyridazin-4(1H)-one,-   3-[1-(2-fluorophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-chlorophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-methoxyphenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-(1-phenyl-1H-pyrazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(3-nitrophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,-   3-[1-(4-methylphenyl)-1H-pyrazol-3-yl]-1-phenylpyridazin-4(1H)-one,-   3-[1-(4-chlorophenyl)-1H-pyrazol-3-yl]-1-phenylpyridazin-4(1H)-one,

a compound of formula:

wherein

Ring A′ is a benzene ring which can be substituted by one substituentselected from a halogen atom, and an alkyl group,

R^(1′) is

(1) an ethyl group, or

(2) a phenyl group which can be substituted by one or more substituentsselected from a fluorine atom, and a trifluoromethyl group,

R^(3′) is a hydrogen atom, or a methyl group, and

Ra is a hydrogen atom, or a C₁₋₄ acyclic hydrocarbon group which can besubstituted,

a compound of formula:

wherein

Ring A″ is a benzene ring which can be substituted by halogen, and

R^(1″) is an acyl group.

Specifically, especially preferable examples of the Compound (I₀)include the following compounds.

-   1-[2-fluoro-4-(3,3,4,4-tetrafluoropyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   1-[2-fluoro-4-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   1-[4-(3,4-difluoro-1H-pyrrol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   1-[4-(4-chloro-1H-pyrazol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   1-[2-fluoro-4-(2-oxo-1,3-oxazolidin-3-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof-   3-[1-(2-fluorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one,    or a salt thereof.-   3-[1-(3-chlorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one,    or a salt thereof.-   1-[4-(4,4-dimethyl-2-oxopyrrolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   1-[4-(5,5-dimethyl-2-oxo-1,3-oxazolidin-3-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.-   5-methoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,    or a salt thereof.

When the compound (I_(o)) is a salt, for example, metal salts, ammoniumsalts, salts with organic bases, salts with inorganic acids, salts withorganic acids, salts with basic or acidic amino acids can be included.Preferable examples of metal salts, for example, include alkali metalsalts such as sodium salts, potassium salts and the like; alkali earthmetal salts such as calcium salts, magnesium salts, barium salts and thelike; and aluminum salts. Preferable examples of salts with organicbases include salts with trimethylamine, triethylamine, pyridine,picoline, 2,6-lutidine, ethanolamine, diethanolamine, triethanolamine,cyclohexylamine, dicyclohexylamine, N, N′-dibenzylethylenediamine andthe like. Preferable examples of salts with inorganic acids includesalts with hydrochloric acid, hydrobromic acid, nitric acid, sulfuricacid, phosphoric acid and the like. Preferable examples of salts withorganic acids include salts with formic acid, acetic acid,trifluoroacetic acid, phthalic acid, fumaric acid, oxalic acid, tartaricacid, maleic acid, citric acid, succinic acid, malic acid,methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid andthe like. Preferable examples of salts with basic amino acids includesalts with arginine, lysine, ornithine and the like. Preferable examplesof salts with acidic amino acids include salts with aspartic acid,glutamic acid and the like. Among them, salts that are pharmacologicallyacceptable are preferable. For example, in the case when acidicfunctional group are present in the compound, for example, inorganicsalts including alkali metal salts (e.g., sodium salts, etc.) and alkaliearth metal salts (e.g., calcium salts, magnesium salts, barium salts,etc.) and ammonium salts are preferable. In contrast, in the case whenbasic functional group are present in the compound, for example, saltswith inorganic acids such as hydrochloric acid, hydrobromic acid, nitricacid, sulfuric acid, phosphoric acid, etc. or salts with organic acidsuch as acetic acid, phthalic acid, fumaric acid, oxalic acid, tartaricacid, maleic acid, citric acid, succinic acid, methanesulfonic acid,p-toluenesulfonic acid, etc. are preferable.

If the compound (I_(o)) includes isomers such as tautomers, opticalisomers, steric isomers, reverse isomers and rotational isomers, one ofthe other isomers or mixture are also included in the compound of thepresent invention. Further, if the compound (I_(o)) has an opticalisomer, the optical isomer separated from the racemate is included inthe compound (I_(o)).

The compound (I_(o)) can be obtained in the crystal form. Either singlecrystalline form or crystalline mixture can be included in the compound(I_(o)).

The compound of the formula (I_(o)) can be a pharmaceutically acceptableco-crystal or a co-crystal salt. The term “co-crystal” or “co-crystalsalt” as used herein means a crystalline material composed of two ormore unique solids at room temperature, each of which has distinctivephysical characteristics such as structure, melting point, and heats offusion, hygroscopicity, solubility, and stability. A co-crystal or aco-crystal salt can be obtained according to a per se knownco-crystallization method.

The compound (I_(o)) can be provided as a solvate (for example, hydrate)or as a non-solvate and both are included in the compound (I_(o)).

The compounds labeled with isotopes (e.g., ²H, ³H, C, ¹⁴C, ¹⁸F, ³⁵S,¹²⁵I, etc.) are also included in the compound (I_(o)).

[Manufacturing Methods]

The compound of the present invention and the compound as raw materialscan be manufactured by the known means, for example, by the methodsshown in the following schemes. Hereinafter, “room temperature”indicates a temperature generally ranging from 0 to 35° C. and “a lowtemperature” indicates a temperature generally from −78 to 0° C.

The compound (I_(o)) can be obtained, for example, by the methodexplained below or by a comparable method thereto. The methods ofmanufacturing the compound (I_(o)) is explained below by explaining themethods of manufacturing the compounds (I-a), (I-b), (I-c), (I-d),(I-e), (I-f), (I-g), (I-h), (I-i), and (I-j) included in the compound(I_(o)).

The symbols used for the compounds in the reaction schemes indicate thesame meanings as mentioned above. In this specification, a methyl group(CH₃) is sometimes abbreviated as Me. The compounds in the schemes caninclude salts thereof in the cases when salts can be formed and suchsalts are similar to the salts of the compound (I_(o)). Further, thecompound obtained in each process can be used directly in the form of areaction mixture or as a crude product in the following reactions.However, it can be isolated from the reaction mixture according to theordinary method. The product itself can be easily purified by the knownmeans of isolation such as extraction, concentration, neutralization,filtration, distillation, recrystallization and chromatography.Alternatively, if the compound in the schemes is commercially available,a commercial product can be used directly and in addition, those whichare manufactured by the known methods or by a comparable method can beused. If the compound as a raw material contains amino, carboxy,hydroxyl or heterocyclic group, the group can be protected by aprotective group that is generally used in the peptide chemistry. Inthis case, if desirable, target compound can be obtained by removing theprotective group. The protective group can be introduced or removed bythe known methods, for example, based on the methods described in“Protective Groups in Organic Synthesis, 3′ Edition” (by Theodora W.Greene, Peter G. M. Wuts, published in 1999 by Wiley-InterscienceCorporation).

Examples of “X⁻” include halogen anions (e.g., chlorine anion, bromineanion, iodine anion, etc.), nitrate ion, and phosphate ion.

In these manufacturing methods, substituent conversions of eachsubstituents of R¹ to R⁹ and each substituents on the Rings A and B becarried out according to the a per se known method, for example, themethod described in “Comprehensive Organic Transformations” (by RichardC. Larock, published in 1999 by Wiley-VCH).

The following respective processes can be carried out without a solventor the raw materials can be dissolved or suspended in an appropriatesolvent prior to the reaction. In this case, one kind of solvent can beused independently or two or more solvents can be combined at anappropriate ratio. Specific examples of the solvents to be used in themanufacturing methods of the present compound are given specifically asfollows: Alcohols: methanol, ethanol, 1-propanol, 2-propanol, tert-butylalcohol, 2-methoxyethanol, etc.

Ethers: diethyl ether, diisopropyl ether, diphenyl ether,tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, etc.

Aromatic hydrocarbons: benzene, chlorobenzene, toluene, xylene, etc.

Saturated hydrocarbons: cyclohexane, hexane, etc.

Amides: N, N-dimethylformamide, N, N-dimethylacetamide,hexamethylphosphoric triamide, etc.

Halogenated hydrocarbons: dichloromethane, chloroform, carbontetrachloride, 1,2-dichloroethane, etc.

Nitriles: acetonitrile, propionitrile, etc.

Sulfoxides: dimethylsulfoxide, etc.

Aromatic organic bases: pyridine, lutidine, etc.

Acid anhydrides: acetic anhydride, etc.

Organic acids: formic acid, acetic acid, propionic acid, trifluoroaceticacid, methanesulfonic acid, etc.

Inorganic acids: hydrochloric acid, sulfuric acid, etc.

Esters: methyl acetate, ethyl acetate, butyl acetate, etc.

Ketones: acetone, methyl ethyl ketone, etc.

Specific examples of bases or deoxidizers that are used in themanufacturing methods for the compound of the present invention aregiven as follows:

Inorganic bases: sodium hydroxide, potassium hydroxide, magnesiumhydroxide, etc.

Basic salts: sodium carbonate, potassium carbonate, cesium carbonate,calcium carbonate, sodium hydrogen carbonate, etc.

Organic bases: triethylamine, diisopropylethylamine, tributylamine,cyclohexyldimethylamine, pyridine, lutidine, 4-dimethylaminopyridine, N,N-dimethylaniline, N-methylpiperidine, N-methylpyrrolidine,N-methylmorpholine, 1,5-diazabicyclo[4.3.0]-5-nonene,1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]-7-undecene,imidazole, etc.

Metal alkoxides: sodium methoxide, sodium ethoxide, potassiumtert-butoxide, etc.

Alkali metal hydrides: sodium hydride, potassium hydride, etc.

Metal amides: sodium amide, lithium diisopropylamide, lithiumhexamethyldisilazide, etc.

Organic lithium reagents: methyl lithium, n-butyl lithium, sec-butyllithium, tert-butyl lithium, etc.

Specific examples of acids or acid catalysts that are used in themanufacturing methods for the compound of the present invention aregiven as follows:

Inorganic acids: hydrochloric acid, sulfuric acid, nitric acid,hydrobromic acid, phosphoric acid, etc.

Organic acids: acetic acid, trifluoroacetic acid, oxalic acid, phthalicacid, fumaric acid, tartaric acid, maleic acid, citric acid, succinicacid, methanesulfonic acid, p-toluenesulfonic acid, 10-camphorsulfonicacid, etc.

Lewis acids: trifluoroboron ether complex, zinc iodide, anhydrousaluminum chloride, anhydrous zinc chloride, anhydrous iron chloride,etc.

When binding “heterocyclic compounds”, “carbamate compounds”, “acetylenederivatives”, “boronic acid derivatives”, or “organotin compounds” toRing A having a leaving group, the product can be produced by a couplingreaction in the presence of a base using both palladium catalyst andcopper catalyst or one of them. The “heterocyclic compounds” include animidazole ring compound, pyrazole ring compound, pyrrolidine ringcompound, azetidine ring compound, a pyrrolidone ring compound,piperidone ring compound, etc., the “carbamate compounds” includeoxazolidone ring compound, etc., the “acetylene derivatives” includecyclopropylacetylene, etc. the “boronic acid derivatives” include(1-methyl-1H-pyrazol-4-yl)boronic acid pinacol esters, etc., the“organotin compounds” includes 2-(tributylstannyl)-1,3-oxazole, etc.

As the “palladium catalyst”, for example,tris(dibenzylideneacetone)dipalladium(0),tetrakistriphenylphosphinepalladium(0) and the like can be used. Thepalladium catalyst can be used in an amount ranging from about 0.01 to 1mol and preferably from 0.05 to 0.2 mol relative to 1 mol of thereaction substrate. The “palladium catalyst” can be used in combinationwith phosphine ligands. When the phosphine ligand is used, it is used inan amount ranging from about 0.01 to 1 mol and preferably from 0.05 to0.2 mol relative to 1 mol of the reaction substrate. As the “phosphineligand”, for example, a phosphine ligand such as triphenylphosphine, and4,5-bis(diphenylphosphino)-9,9-dimethylxanthene are exemplified. As the“copper catalysts”, for example, cuprous iodide (CuI), and copper oxide(Cu₂O) can be used. The “copper catalyst” can be used in an amountranging from about 0.1 to 1 mol and preferably from 0.1 to 0.5 molrelative to 1 mol of the reaction substrate. In addition, the “coppercatalyst” can be used along with a ligand such as N,N′-dimethylethane-1,2-diamine, trans-1,2-diaminocyclohexane andsalicylaldoxime. Such a ligand is used in an amount ranging from about0.1 to 4 mol and preferably from 0.1 to 2 mol relative to 1 mol of thereaction substrate. As the “base”, sodium tert-butoxide or potassiumphosphate can be used and the amount ranges from about 1 to 10 mol andpreferably from 1 to 3 mol relative to 1 mol of the reaction substrate.It is advantageous to carry out the present reaction in the absence of asolvent or in the presence of an inert solvent in the reaction. Thesolvent to be used is not particularly limited as long as the reactionproceeds, but for example, ethers, nitriles and the like are desirable.It is desirable to carry out the reaction generally at room temperatureor under reflux conditions by heating and preferably under refluxconditions by heating. The reaction time generally ranges from 0.5 to 48hours and preferably from 1 to 24 hours.

This coupling reaction can be carried out by the methods described in“Cross-Coupling Reactions: A Practical Guide (Topics in CurrentChemistry)” (Springer) “Experimental Organic Metallic Chemistry forSynthesizing Chemists” (Kodansha) and “Organic Synthesis usingTransition Metals” (Kagaku Dojin) or by a comparable method.

The compounds (I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), (I-h),(I-i), and (I-j), each of which is included in the compound (I₀) can beprepared by the manufacturing method A, manufacturing method B,manufacturing method C, manufacturing method D, manufacturing method E,manufacturing method F, manufacturing method G, manufacturing method H,manufacturing method I or manufacturing method J as explained below.

The symbols in each general formula in the reaction schemes representthe same meanings as mentioned above unless otherwise specificallymentioned.

[Manufacturing Method A]

[Manufacturing Method B]

[Manufacturing Method C]

[Manufacturing Method D]

[Manufacturing Method E]

[Manufacturing Method F]

[Manufacturing Method G]

[Manufacturing Method H]

[Manufacturing Method I]

[Manufacturing Method J]

Process 1 is a method of producing a compound (III) by reacting acompound (II) with a diazotization agent. If desirable, the reaction canbe carried out in the presence of an acid.

Examples of a diazotization agent are as follows: alkali metal nitritessuch as sodium nitrite and potassium nitrite; C₂₋₆ nitrous acid alkylesters such as t-butyl nitrite and isoamyl nitrite; nitrosyl chloride,nitrosyl sulfate, and nitrogen monoxide. Among them, sodium nitrite isdesirable from the standpoint that it can be obtained easily at a lowcost. Further, nitrous acid alkyl esters are desirable from thestandpoint that the reactivity is enhanced. In this case, since analkali metal nitrite is solid at room temperature, it is dissolved inadvance in water prior to its use.

As the “acid”, for example, hydrochloric acid, sulfuric acid and aceticacid are applicable and they can be also used as a mixture.

From the standpoint of increasing reactivity and economical efficiency,the amount of a diazotization agent ranges from 1 to 5 mol andpreferably from 1 to 2 mol relative to 1 mol of the compound (II). It isdesirable to carry out the reaction generally at room temperature or ata low temperature and preferably at a temperature ranging from −30° C.to 0° C.

The reaction time generally ranges from 1 minute to 3 hours andpreferably from 1 minute to 1 hour.

It is advantageous to carry out the present reaction in the absence of asolvent or in the presence of an inert solvent in the reaction. Thesesolvents are not limited as long as the reaction proceeds, but water ispreferred.

Process 2 is a method of producing a compound (V), a compound (IX), acompound (XVIII) or a compound (XXVIII) by placing a compound (III)together with a compound (IV), a compound (VIII), a compound (XVII) or acompound (XXVII).

This process can be carried out by the method described in TetrahedronLett., 2008, 49(14), 2262-2264 or by a comparable method. If desirable,the reaction can be carried out in the presence of a base.

The amount of the compounds (IV), (VIII), (XVII) or (XXVII) to be usedranges from approximately 1 to 5 mol and preferably from 1 to 2 molrelative to 1 mol of the compound (III).

As the “base”, for example, sodium acetate can be used.

The amount of the “base” to be used generally ranges from 1 to 10equivalents and preferably from 2 to 6 equivalents relative to thecompound (III).

It is advantageous to carry out the present reaction in the absence of asolvent or in the presence of an inert solvent in the reaction. Thesesolvents are not limited as long as the reaction proceeds, but a mixedsolvent of alcohols and water is desirable.

It is desirable to carry out the reaction generally at room temperatureor at a low temperature while being cooled in an ice bath.

The reaction time generally ranges from 5 seconds to 24 hours andpreferably ranges from 5 seconds to 1 hour.

R⁴ is a C₁₋₁₀ alkyl group which can be substituted, and preferably amethyl group, or an ethyl group. In this process, R² represents a C₁₋₁₀alkyl group which can be substituted or a C₁₋₁₀ alkoxy group which canbe substituted.

Process 3 is a method of producing a compound (VI), a compound (X), acompound (XIX), a compound (XXIII) or a compound (XXXIV) from thecompound (V), the compound (IX), the compound (XVIII), the compound(XXII) or the compound (XXXIII). The reaction can be carried out in thepresence of N, N-dimethylformamide dimethylacetal and the like as asolvent.

This process can be carried out by the method described in the Journalof Heterocyclic Chemistry, 1981, 18, 333-334 or by a comparable method.

It is desirable to carry out the reaction generally under refluxconditions by heating and preferably at 100° C. to 150° C.

The reaction time generally ranges from 1 to 10 hours and preferablyfrom 1 to 5 hours.

Process 4 is a method of producing a compound (I-a), a compound (I-e) ora compound (XXXV) by placing the compound (VII) together with thecompound (VI), the compound (XXIII) or the compound (XXXIV).

The amount of the compound (VII) to be used ranges from approximately 1to 10 mol and preferably from approximately 2 to 5 mol relative to 1 molof the compound (VI), the compound (XXIII) or the compound (XXXIV).

It is advantageous to carry out the reaction in the absence of a solventor in the presence of an inert solvent in the reaction. The solvent tobe used is not limited as long as the reaction proceeds, but alcohols,organic acids or mixed solvents thereof are desirable.

It is desirable to carry out the reaction generally in an ice bath, atroom temperature, or under reflux conditions by heating and preferablyat 0° C. to 150° C.

The reaction time generally ranges from 0.1 to 10 hours and preferablyfrom 0.5 to 5 hours.

This process can be carried out by the method described in the Journalof Heterocyclic Chemistry, 1981, 18, 333-334 or by a comparable method.

In this process, R¹ represents a C₁₋₁₀ alkyl group which can besubstituted, a C₃₋₇ cycloalkyl group which can be substituted, or anaromatic group which can be substituted.

Process 5 is a method of producing a compound (XI) by reacting thecompound (X) with hydrazine, a method of producing a compound (XIII) byreacting the compound (X) with ammonia, or a method of producing acompound (XV) by reacting the compound (X) with an amine compound (XII).

The amount of hydrazine, ammonia and the amine compound (XII) to be usedranges from approximately 1 to 10 mol and preferably from approximately2 to 5 mol relative to 1 mol of the compound (X).

It is advantageous if the reaction is carried out in the absence of asolvent or in the presence of an inert solvent in the reaction. Thesolvent is not limited as long as the reaction proceeds, but forexample, alcohols or ethers are desirable.

It is desirable to carry out the reaction generally under heatedconditions and preferably at 50° C. to 100° C.

The reaction time generally ranges from 1 to 10 hours and preferablyfrom 1 to 5 hours.

This process can be carried out by the method described in the Journalof Heterocyclic Chemistry, 1981, 18, 333-334 or by a comparable method.

Further, a method of heating under microwave conditions or a method ofheating in the presence of trimethyl aluminum as an activator isapplicable.

The reaction temperature in the case when heating under microwaveconditions range generally from 50° C. to 150° C. and preferably from100° C. to 130° C. The reaction time generally ranges from 10 to 60 min.and preferably from 10 to 20 min. It is advantageous to carry out thereaction in the absence of a solvent or using an inert solvent in thereaction. The solvent is not limited as long as the reaction proceeds,but for example, alcohols or ethers are desirable.

If the reaction is carried out in the presence of trimethyl aluminum asan activator, trimethyl aluminum is used in an amount ranging fromapproximately 1 to 5 mol and preferably from about 1 to 3 mol relativeto 1 mol of the compound (X). It is advantageous to carry out thereaction in the absence of a solvent or using an inert solvent in thereaction. The solvent is not limited as long as the reaction proceeds,but methylene chloride is desirable. It is desirable to carry out thereaction generally under heated conditions and preferably at 50° C. to100° C. The reaction time generally ranges from 1 to 15 hours andpreferably from 1 to 10 hours.

Process 6 is a method of producing a compound (I-b) by placing thecompound (XI) together with an amine compound (XII).

In the case when R⁵ is a hydrogen, the compound (XI) is reacted with N,N-dimethylformamide dimethylacetal or the like, and subsequently reactedwith an amine compound (XII) under an acidic condition without isolationto produce a compound (I-b). In contrast, if R⁵ is a methyl group, thecompound (XI) is reacted with N, N-dimethylacetamide dimethylacetal andthe reaction is carried out with an amine compound (XII) under an acidiccondition as mentioned above to produce a compound (I-b).

The amount of N, N-dimethylformamide dimethylacetal or N,N-dimethylacetamide dimethylacetal to be used ranges from about 1 to 5mol and preferably from about 1 to 2 mol relative to 1 mol of thecompound (XI).

It is desirable to carry out the reaction generally under heatedconditions and preferably at 50° C. to 100° C.

The reaction time generally ranges from 0.5 to 3 hours and preferablyfrom 0.5 to 1 hour.

It is advantageous to carry out the reaction in the absence of a solventor using an inert solvent in the reaction. The solvent is not limited aslong as the reaction proceeds, but for example, nitriles are desirable.

The amount of an amine compound (XII) to be used ranges from about 1 to5 mol and preferably from 1 to 2 mol relative to 1 mol of the compound(XI).

As the “acid”, for example, acetic acid can be used.

As for the amount of an acid to be used, it is desirable to use the sameamount as acetonitrile used as a solvent in the aforementioned reaction.

It is desirable to carry out the reaction generally under heatedconditions and preferably at 100° C. to 130° C.

The reaction time generally ranges from 0.5 to 3 hours and preferablyfrom 0.5 to 1 hour.

This process can be carried out by the method described in Org. Lett.,2004, 6 (17), 2969-2971 or by a comparable method.

Process 7 is a method of producing a compound (XIV) from the compound(XIII). The product can be produced in the presence of N,N-dimethylformamide dimethylacetal as a solvent.

It is desirable to carry out the reaction generally under heatedconditions and preferably at 100° C. to 150° C.

The reaction time generally ranges from 0.1 to 5 hours and preferablyfrom 0.1 to 1 hour.

This process can be carried out by the method described in Arch. Pharm.Chem. Life Sci., 2007, 340, 17-25 or by a comparable method.

Process 8 is a method of producing a compound (I-c) by placing thecompound (XIV) together with a hydrazine compound (VII). The reactioncan be carried out in the presence of an organic acid.

The amount of the hydrazine compound (VII) to be used ranges from about1 to 5 mol and preferably from 1 to 2 mol relative to 1 mol of thecompound (XIV).

As the “organic acid”, for example, acetic acid can be used.

The amount of the organic acid to be used is similar to the amount whenit is generally used as a solvent.

It is desirable to carry out the reaction generally under heatedconditions and preferably at 100° C. to 130° C.

The reaction time generally ranges from 0.5 to 3 hours and preferablyfrom 0.5 to 1 hour.

This process can be carried out by the method described in Arch. Pharm.Chem. Life Sci., 2007, 340, 17-25 or by a comparable method.

Process 9 is a method of producing a compound (XVI) from the compound(XV). The reaction can be carried out in the presence of1H-benzo[d][1,2,3]triazole and an acid halide.

It is advantageous to carry out the reaction in the absence of a solventor using an inert solvent in the reaction. The solvent is notparticularly limited as long as the reaction proceeds, but for example,halogenated hydrocarbons are desirable.

The amount of 1H-benzo[d][1,2,3]triazole to be used ranges from about 1to 10 mol and preferably from 1 to 5 mol relative to 1 mol of thecompound (XV).

As the “acid halide”, for example, thionyl chloride can be used.

The amount of the “acid halide” to be used ranges from about 1 to 5equivalents and preferably from 1 to 2 equivalents relative to thecompound (XV).

It is desirable to carry out the reaction under reflux conditions byheating and it is also possible to carry out the reaction in a shorttime under microwave conditions. If the reaction is carried out undermicrowave conditions, the reaction time ranges from 0.1 to 1 hour at 80watts and preferably from 0.1 to 0.3 hours.

This process can be carried out by the method described in Synthesis,2007, 1204-1208 or by a comparable method.

Process 10 is a method of producing a compound (I-d) from the compound(XVI). The product can be produced by reacting an acid as well as sodiumazide in the presence of a phase transfer catalyst.

It is advantageous to carry out the reaction using an inert solvent inthe reaction. The solvent to be used is not particularly limited as longas the reaction proceeds, but for example, it is desirable to use ahalogenated hydrocarbon, a solvent mixed with water and the like.

As the “phase transfer catalyst, for example, tetrabutyl ammoniumbromide can be used.

The amount of the “phase transfer catalyst” to be used ranges from about0.1 to 1 equivalent and preferably from 0.1 to 0.3 equivalent relativeto the compound (XVI).

The amount of sodium azide to be used ranges from about 1 to 5 mol andpreferably from 1 to 3 mol relative to 1 mol of the compound (XVI).

As the “acid”, for example, organic acids can be used.

The amount of the “acid” to be used ranges from about 1 to 5 equivalentsand preferably from 1 to 2 equivalents relative to the compound (XVI).

The reaction temperature can range from 0° C. to 100° C. and preferablyat room temperature.

The reaction time generally ranges from 1 to 48 hours and preferablyfrom 10 to 24 hours.

This process can be carried out by the method described in Synthesis,2007, 1204-1208 or by a comparable method.

Process 11 is a method of producing a compound (XX) or a compound (XXXI)from the compound (XIX) or the compound (XXX). The reaction can becarried out under an acidic or basic condition. It is advantageous tocarry out this reaction without using a solvent or using an inertsolvent in the reaction. The solvent to be used is not particularlylimited as long as the reaction proceeds, but for example, it isdesirable to use alcohols, a solvent mixed with water and ethers.

As the “acid”, for example, inorganic acids can be used.

As the “base”, for example, inorganic bases such as sodium hydroxide orpotassium hydroxide can be used. Further, lithium hydroxide can also beused.

The amount of the acid or the base to be used ranges from about 1 to 10mol and preferably from 1 to 5 mol relative to 1 mol of the compound(XIX) or the compound (XXX).

It is desirable to carry out the reaction generally at room temperatureor under heated conditions and preferably at room temperature.

The reaction time generally ranges from 1 to 48 hours and preferablyfrom 3 to 10 hours.

Process 12 is a method of producing a compound (XXI) or a compound(XXXII) from the compound (XX) or the compound (XXXI). The product canbe produced using N, O-dimethylhydroxylamine hydrochloride with acondensation agent in the presence of a base such as triethylamine orN,N-diisopropylethylamine. Alternatively, a carboxylic acid of thesubstrate is converted to a corresponding acid halide which is thenreacted with N, O-dimethylhydroxylamine hydrochloride to produce thetarget products.

As the “condensation agent”, for example,1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride can be usedin the presence of 1-hydroxybenzotriazole.

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,nitriles, ethers and amides are desirable.

The amount of the condensation agent to be used ranges from about 1 to 5mol and preferably from 1 to 3 mol relative to 1 mol of the compound(XX) or the compound (XXXI).

A base such as triethylamine or N,N-diisopropylethylamine is preferablyused in an amount ranging from about 1 to 10 mol and preferably from 2to 3 mol relative to 1 mol of the compound (XX) or the compound (XXXI).

It is desirable to carry out the reaction generally at room temperatureor under heated conditions and preferably at room temperature.

The reaction time generally ranges from 1 to 48 hours and preferablyfrom 5 to 10 hours.

The reaction with an acid halide is carried out in the presence of abase such as triethylamine using N, O-dimethylhydroxylaminehydrochloride to synthesize a target product.

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,ethers, esters amides are desirable.

The amount of the base such as triethylamine ranges from about 1 to 10mol and preferably from 2 to 3 mol relative to 1 mol of the compound(XX) or the compound (XXXI).

It is desirable to carry out the reaction generally while cooling in anice bath or at room temperature and preferably by cooling in an icebath.

The reaction time generally ranges from 0.5 to 5 hours and preferablyfrom 1 to 3 hours.

Further, the compound (XXI) or the compound (XXXII) can be produced byreacting the compound (XIX) or the compound (XXX) with trimethylaluminum and N, O-dimethylhydroxylamine hydrochloride in the presence ofan organic base. The amount of an organic base, trimethyl aluminum andN, O-dimethylhydroxylamine hydrochloride ranges from about 1 to 10 moland preferably from 2 to 5 mol relative to 1 mol of the compound (XIX)or the compound (XXX). It is advantageous to carry out this reactionwithout using a solvent or using an inert solvent in the reaction. Thesolvent to be used is not particularly limited as long as the reactionproceeds, but for example, halogenated hydrocarbons are desirable. It isdesirable to carry out the reaction generally by cooling in an ice bathor at room temperature and preferably by cooling in an ice bath. Thereaction time generally ranges from 1 to 24 hours and preferably from 1to 5 hours.

Process 13 is a method of producing a compound (XXII) or a compound(XXXIII) from the compound (XXI) or the compound (XXXII). The productcan be produced using an “alkylating agent” such as a Grignard reagentor an organic lithium reagent.

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,ethers are desirable.

The amount of the “alkylating agent” ranges from about 1 to 10 mol andpreferably from 2 to 3 mol relative to 1 mol of the compound (XXI) orthe compound (XXXII).

It is desirable to carry out the reaction generally at −78° C. or whilecooling in an ice bath and preferably at −78° C.

R⁷ is a hydrogen atom, or a C₁₋₁₀ alkyl group which can be substituted,and preferably a hydrogen atom, or a methyl group.

R⁸ is a hydrogen atom, or a C₁₋₁₀ alkyl group which can be substituted,and preferably a hydrogen atom, or a methyl group.

The reaction time generally ranges from 1 to 10 hours and preferablyfrom 1 to 3 hours.

Process 14 is a method of producing a compound (XXIV) from the compound(XX). The product can be produced using diphenylphosphoryl azide in thepresence of a base such as triethylamine.

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds. For example, inthe case when using tert-butanol as a solvent, a tert-butyl carbamatederivative is temporarily obtained and its hydrolysis is carried outunder an acidic condition to produce a compound (XXIV). Further, in thecase when using toluene as a solvent, an isocyanate as an intermediateis hydrolyzed with an aqueous sodium hydroxide solution to produce acompound (XXIV).

The amount of diphenylphosphoryl azide ranges from about 1 to 10 mol andpreferably from 1 to 3 mol relative to 1 mol of the compound (XX).

The amount of triethylamine ranges from about 1 to 10 mol and preferablyfrom 1 to 3 mol relative to 1 mol of the compound (XX).

It is desirable to carry out the reaction generally at room temperatureor under reflux conditions by heating and preferably under refluxconditions by heating.

The reaction time generally ranges from 1 to 20 hours and preferablyfrom 1 to 10 hours.

This process can be carried out by the method described in Tetrahedron1974, 30, 2151-2157 or by a comparable method.

Process 15 is a method of producing a compound (XXV) from the compound(XXIV). The product can be produced using a nitrite in the presence of acopper salt.

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,amides are desirable.

As the “copper salt”, cupric bromide (CuBr₂) and the like can be usedand its amount ranges from about 1 to 5 mol and preferably from 1 to 2mol relative to 1 mol of the compound (XXIV).

As the “nitrite”, isoamyl nitrite or pentyl nitrite and the like can beused and its amount ranges from about 1 to 10 mol and preferably from 1to 3 mol relative to 1 mol of the compound (XXIV).

It is desirable to carry out the reaction generally in an ice bath, atroom temperature or under heated conditions and preferably at atemperature ranging from 0 to 70° C.

The reaction time generally ranges from 1 to 10 hours and preferablyfrom 1 to 5 hours.

This process can be carried out by the method described in U.S. Pat. No.5,059,599 or by a comparable method.

Process 16 is a method of producing a compound (I-f) from the compound(XXV) and the compound (XXVI). The product can be produced using apalladium catalyst in the presence of a base.

The amount of the compound (XXVI) to be used ranges from approximately 1to 10 mol and preferably from approximately 1 to 3 mol relative to 1 molof the compound (XXV).

As the “base”, potassium acetate or potassium carbonate and the like canbe used and its amount ranges from about 1 to 10 mol and preferably from1 to 3 mol relative to 1 mol of the compound (XXV).

As the “palladium catalyst”,bis[di-tert-butyl(4-dimethylaminophenyl)phosphine]dichloropalladium(II)or tetrakis(triphenylphosphine)palladium and the like can be used andits amount ranges from about 0.01 to 0.5 mol and preferably from 0.03 to0.1 mol relative to 1 mol of the compound (XXV).

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,alcohols, solvent mixture with water, aromatic hydrocarbons, ethers,amides and the like are desirable.

It is desirable to carry out the reaction generally at room temperatureor under reflux conditions by heating and preferably under refluxconditions by heating.

The reaction time generally ranges from 5 to 48 hours and preferablyfrom 10 to 20 hours.

This process can be carried out by the method described in Org. Lett.,2006, 8, 1787-1789 or by a comparable method.

R⁹ represents an alkoxy group which can be substituted or a hydroxylgroup and the like.

Process 17 is a method of producing a compound (XXIX) from the compound(XXVIII) and the reaction can be carried out in the presence of a base.

As the base, basic salts, organic bases, metal alkoxides or metal amidesand the like can be used and potassium carbonate or sodium methoxide isdesirable. The amount of the base ranges from about 1 to 10 mol andpreferably from 1 to 3 mol relative to 1 mol of the compound (XXVIII).It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,ethers or amides are desirable. It is desirable to carry out thereaction generally at room temperature or under reflux conditions byheating and preferably at room temperature.

The reaction time generally ranges from 1 to 24 hours and preferablyfrom 2 to 4 hours.

Process 18 is a method of producing a compound (XXX) or a compound (I-g)from the compound (XXIX) or the compound (XXXVI).

Methylation can be carried out under the condition usingtrimethylsilyldiazomethane or methyl iodide in the presence of a base.

In the case when the reaction is carried out usingtrimethylsilyldiazomethane, trimethylsilyldiazomethane is used in anamount ranging from about 10 to 50 mol and preferably from 5 to 20 molrelative to 1 mol of the compound (XXIX) or the compound (XXXVI) using asolvent such as methanol and the like. It is desirable to carry out thereaction generally by cooling in an ice bath or under room temperatureconditions and preferably by cooling in an ice bath.

The reaction time generally ranges from 1 to 5 hours and preferably from1 to 2 hours.

In the case when using methyl iodide in the presence of a base, thereaction can be carried out using an ether solvent in the presence ofsodium hydroxide and the like.

Methyl iodide is used in an amount ranging from about 1 to 10 mol andpreferably from 1 to 3 mol relative to 1 mol of the compound (XXIX) orthe compound (XXXVI). In addition, a base such as sodium hydroxide isalso used in an amount ranging from about 1 to 10 mol and preferablyfrom 1 to 3 mol relative to 1 mol of the compound (XXIX) or the compound(XXXVI). It is desirable to carry out the reaction generally by coolingin an ice bath or under room temperature conditions and preferably bycooling in an ice bath.

The reaction time generally ranges from 1 to 5 hours and preferably from1 to 2 hours.

Process 19 is a method of producing a compound (XXXVI) from the compound(XXXV) and the product can be obtained using trimethylsilyl chloride inthe presence of sodium iodide.

The amount of sodium iodide ranges from about 1 to 10 mol and preferablyfrom 1 to 5 mol relative to 1 mol of the compound (XXXV). The amount oftrimethylsilyl chloride ranges from about 1 to 10 mol and preferablyfrom 1 to 5 mol relative to 1 mol of the compound (XXXV).

It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,nitriles are desirable. It is desirable to carry out the reactiongenerally at room temperature or under reflux conditions by heating andpreferably under reflux conditions by heating. The reaction timegenerally ranges from 1 to 20 hours and preferably from 3 to 10 hours.

Process 20 is a method of producing a compound (XXXVII) from thecompound (XIX) and the product can be obtained using an appropriatereductant.

As the “reductant”, lithium aluminum hydride, diisobutylaluminum hydrideand the like can be used. It can be used in an amount ranging from about1 to 10 mol and preferably from 1 to 3 mol relative to 1 mol of thecompound (XIX). It is advantageous to carry out this reaction withoutusing a solvent or using an inert solvent in the reaction. The solventto be used is not particularly limited as long as the reaction proceeds,but for example, ethers are desirable. It is desirable to carry out thereaction generally at −78° C. or by cooling in an ice bath andpreferably at −78° C.

The reaction time generally ranges from 0.5 to 5 hours and preferablyfrom 1 to 3 hours.

This process can be carried out by the method described in ComprehensiveOrganic Transformations (WILEY-VCH) or by a comparable method.

Process 21 is a method of producing a compound (XXXVIII) from thecompound (XXXVII) and the product can be produced using an appropriateoxidation.

As the “oxidation”, for example, Swern oxidation, or oxidation using anoxidant such as a sulfur trioxide pyridine complex, pyridiniumchlorochromate and the like can be used. When the oxidation using theoxidant is conducted, the oxidant is used in the amount ranging fromabout 1 to 10 mol and preferably from 1 to 3 mol relative to 1 mol ofthe compound (XXXVII). It is advantageous to carry out this reactionwithout using a solvent or using an inert solvent in the reaction. Thesolvent to be used is not particularly limited as long as the reactionproceeds, but for example, dimethylsulfoxide, halogenated hydrocarbons,ethers and esters are desirable. It is desirable to carry out thereaction generally under low temperature conditions or at roomtemperature. The reaction time generally ranges from 1 to 10 hours andpreferably from 1 to 3 hours.

This process can be carried out by the method described in ComprehensiveOrganic Transformations (WILEY-VCH) or in Oxidation in Organic Chemistry(American Chemical Society) by a comparable method.

Process 22 is a method of producing a compound (I-h) from the compound(XXXVIII). Using ca-tosyl benzyl isocyanide (Organic Syntheses, Coll.Vol. 10, p 692 (2004): Vol. 77, p 198 (2000)), an 1,3-oxazole compoundor an 1,3-imidazole compound can be produced. In the case when producing“1,3-oxazole compound”, the reaction is carried out in the presence of abase such as potassium carbonate. In contrast, in the case whenproducing “1,3-imidazole compound”, the reaction is carried out in thepresence of a base such as potassium carbonate along with the presenceof aqueous ammonia or an amine such as methylamine.

A base such as potassium carbonate, aqueous ammonia or methylamine isused in an amount ranging from about 1 to 10 mol and preferably from 1to 3 mol relative to the compound (XXXVIII). It is advantageous to carryout this reaction without using a solvent or using an inert solvent inthe reaction. The solvent to be used is not particularly limited as longas the reaction proceeds, but for example, ethers, nitriles and amidesare desirable. It is desirable to carry out the reaction generally underlow temperature conditions or at room temperature and preferably underroom temperature conditions.

The reaction time generally ranges from 5 to 30 hours and preferablyfrom 5 to 15 hours.

This process can be carried out by the method described in New Edition:Heterocyclic Compounds (Kodansha) or by a comparable method.

Process 23 is a method of producing a compound (I-i) from the compound(XXIV). As long as the reaction proceeds, it is not particularlylimited, but after reacting with an aqueous glyoxal solution in analcoholic solvent, under an acidic condition, the compound (XXIV) can bereacted with ammonium chloride and benzaldehyde to give the compound(I-i).

An aqueous glyoxal solution is used in an amount ranging from about 1 to5 mol and preferably from 1 to 3 mol relative to 1 mol of the compound(XXIV). It is desirable to carry out the reaction generally under lowtemperature conditions or under room temperature conditions andpreferably under room temperature conditions.

The reaction time generally ranges from 5 to 30 hours and preferablyfrom 10 to 20 hours.

Benzaldehyde and ammonium chloride are used in an amount ranging fromabout 1 to 5 mol and preferably from 1 to 3 mol relative to 1 mol of thecompound (XXIV). An acid to be used is not particularly limited as longas the reaction proceeds, but for example, phosphoric acid and the likeare desirable. It is desirable to carry out the reaction generally underroom temperature conditions or under reflux conditions by heating andpreferably under reflux conditions by heating. The reaction timegenerally ranges from 5 to 40 hours and preferably from 20 to 30 hours.

This process can be carried out by the method described in New Edition:Heterocyclic Compounds (Kodansha) or by a comparable method.

Process 24 is a method of producing a compound (XXXIX) from the compound(XXV). As long as the reaction proceeds, it is not particularly limited,but the product can be produced by reacting the compound (XXV) withtrimethylsilylacetylene in an ether solvent such as tetrahydrofuran inthe presence of a palladium catalyst and a copper catalyst as well as abase. As the palladium catalyst, for example,bis(triphenylphosphine)palladium (II) dichloride and the like can beused. The palladium catalyst is used in an amount ranging from about0.01 to 1 mol and preferably from 0.05 to 0.2 mol relative to 1 mol ofthe compound (XXV). In addition, the palladium catalyst is used alongwith a phosphine ligand such as triphenylphosphine. The phosphine ligandis used in an amount ranging from about 0.01 to 1 mol and preferablyfrom 0.05 to 0.2 mol relative to 1 mol of the compound (XXV). As thecopper catalyst, for example, cuprous iodide (CuI) and the like can beused. The copper catalyst is used in an amount ranging from about 0.1 to1 mol and preferably from 0.1 to 0.5 mol relative to 1 mol of thecompound (XXV). Trimethylsilylacetylene is used in an amount rangingfrom about 1 to 5 mol and preferably from 1 to 3 mol relative to 1 molof the compound (XXV). The reaction is carried out in the presence of abase such as triethylamine and the amount of a base to be used rangesfrom about 1 to 5 mol and preferably from 1 to 3 mol relative to 1 molof the compound (XXV). It is desirable to carry out the reactiongenerally by heating at a temperature ranging from 40 to 60° C.

The reaction time generally ranges from 1 to 10 days and preferably from5 to 7 days.

This process can be carried out by the method described in TetrahedronLett., 1975, 16, 4467-4470 or by a comparable method.

Process 25 is a method of producing a compound (XL) from the compound(XXXIX). As long as the reaction proceeds, it is not particularlylimited, but the product can be produced by reacting the compound(XXXIX) with sodium hydroxide aqueous solution or a fluoride ion such astetrabutylammonium fluoride in an alcohol or an ether as a solvent. Theamount of aqueous sodium hydroxide solution or fluoride ion ranges fromabout 1 to 100 mol or greater and preferably from 1 to 3 mol relative to1 mol of the compound (XXXIX). It is desirable to carry out the reactiongenerally by cooling in an ice bath or under room temperature conditionsand preferably under room temperature conditions. The reaction timegenerally ranges from 0.5 to 5 hours and preferably from 1 to 3 hours.

Process 26 is a method of producing a compound (I-j) from the compound(XL). As long as the reaction proceeds, it is not particularly limited,but the product can be produced by reacting the compound (XL) withN-hydroxybenzenecarboximidoyl chloride in an ether as a solvent.N-hydroxybenzenecarboximidoyl chloride is used in an amount ranging fromabout 1 to 5 mol and preferably from 1 to 3 mol relative to 1 mol of thecompound (XL). The present reaction is carried out in the presence of abase such as triethylamine and the amount of a base to be used rangesfrom about 1 to 5 mol and preferably from 1 to 3 mol relative to 1 molof the compound (XL). It is desirable to carry out the reactiongenerally by cooling in an ice bath or under room temperature conditionsand preferably under room temperature conditions. The reaction timegenerally ranges from 1 to 48 hours and preferably from 5 to 20 hours.

This process can be carried out by the method described in “New Edition:Heterocyclic Compounds” (Kodansha) or by a comparable method.

The compound (I-e) wherein R² is a halogen atom (e.g., a bromine atom)can be produced by the following method. Initially, the compound (V) isreacted with a reagent such as N,N-dimethylformamide dimethyl acetal toobtain a compound (XXII) wherein R² and R⁷ are hydrogen atoms. Theamount of the reagent such as N,N-dimethylformamide dimethyl acetal isabout 1 to 5 mol, preferably 1 to 2 mol relative to 1 mol of thecompound (V). It is desirable that this reaction is carried out using aninert solvent in the reaction (e.g., amides). It is desirable that thereaction is carry out at room temperature or while heating andpreferably at a temperature ranging from 40 to 100° C. The reaction timegenerally ranges from 1 to 20 hours, and preferably from 1 to 10 hours.Then, the obtained compound (XXII) is reacted with a halogen molecule(e.g., a bromine molecule) to introduce a halogen atom at R² position ofthe compound (XXII). The amount of the halogen molecule to be usedranges from about 1 to 5 mol and preferably about 1 to 2 mol relative to1 mol of the compound (XXII). It is desirable that this reaction iscarried out using an inert solvent in the reaction (e.g., organicacids). It is desirable that the reaction is carried out at roomtemperature or at a low temperature and preferably at room temperature.The reaction time generally ranges from 1 to 10 hours, and preferablyfrom 1 to 3 hours.

The compound (I-e) wherein R⁸ is an alkyl group (e.g., a methyl group)can be produced by the following method. Initially, the compound (XXII)is reacted with a reagent such as N,N-dimethylacetamide dimethyl acetalto obtain a compound (XIII). The amount of N,N-dimethylacetamidedimethyl acetal to be used ranges from about 1 to 30 mol and preferablyfrom 5 to 20 mol relative to 1 mol of the compound (XXII). This reactionis preferably carried out without using a solvent or using an inertsolvent in the reaction. Further, it is desirable to carry out thereaction under reflux conditions by heating, or it is possible to beheated under microwave conditions. The reaction temperature when heatingunder microwave conditions generally ranges from 50° C. to 150° C. andpreferably at a temperature ranging from 100° C. to 130° C. The reactiontime generally ranges from 1 to 60 min. and preferably from 3 to 20 min.

The compound (I-e) wherein R⁸ is an alkyl group which is substituted bya fluorine atom (e.g., a trifluoromethyl group) can be produced by thefollowing method. Initially, the compound (XXII) is reacted with anester having an alkyl group substituted with a fluorine atom (e.g.,ethyl trifluoroacetate) under basic conditions. The amount of the esterto be used ranges from 1 to 20 mol and preferably from 1 to 10 molrelative to 1 mol of the compound (XXII). This reaction is carried outin the presence of a base such as sodium methoxide and the amount of thebase to be used ranges from about 1 to 5 mol and preferably from 1 to 3mol relative to 1 mol of the compound (XXII). It is desirable that thisreaction is carried out using an inert solvent in the reaction (e.g.,ethers). It is desirable to carry out the reaction under ice coldconditions or at room temperature and preferably at room temperature.The reaction time generally ranges from 0.5 to 7 days and preferablyfrom 1 to 3 days. Furthermore, the compound (I-e) can be produced byplacing the reaction product along with the compound (VII). The amountof the compound (VII) to be used ranges from about 1 to 10 mol andpreferably from about 2 to 5 mol relative to 1 mol of the raw material.It is advantageous to carry out this reaction without using a solvent orusing an inert solvent in the reaction. The solvent to be used is notparticularly limited as long as the reaction proceeds, but for example,alcohols and organic acids or mixed solvents thereof are desirable. Itis desirable to carry out the reaction under ice cold conditions or atroom temperature or while heating and preferably at a temperatureranging from 0° C. to 150° C. The reaction time generally ranges from0.1 to 10 hours and preferably from 0.5 to 5 hours. This process can becarried out by the method described in the Journal of HeterocyclicChemistry, 1981, 18, 333-334 or by a comparable method.

The compound (I-e) wherein R⁷ is a halogen atom (e.g., a fluorine atom)can be produced by reacting the compound (I-e) wherein R⁷ is a hydrogenatom with a reagent such as a halogenating agent. For example, whenintroducing a fluorine atom,1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octanebis(tetrafluoroborate) (hereinafter referred to as Selectfluor) can beused as a fluorinating agent. The amount of the Selectfluor to be usedranges from about 1 to 30 mol and preferably from 5 to 20 mol relativeto 1 mol of the compound (I_(−e)). This reaction is preferably carriedout using an inert solvent in the reaction (e.g., nitriles, etc.).Further, It is desirable to carry out the reaction under ice coldconditions or at room temperature and preferably at room temperature.The reaction time generally ranges from 1 to 20 days and preferably from5 to 15 days.

The compound (I-e) wherein R⁷ is an alkyl group (e.g., a methyl group)can be produced by the following reaction. Initially, the compound(XXII) is reacted with an ester (e.g., methyl formate) under basicconditions. The ester is works also as a solvent. This reaction iscarried out in the presence of a base such as sodium methoxide, and theamount of the base to be used ranges from about 1 to 5 mol andpreferably from 1 to 3 mol relative to 1 mol of the compound (XXII).Generally, it is desirable to carry out the reaction under ice coldconditions or at room temperature and preferably at room temperature.The reaction time generally ranges from 1 to 20 hours and preferablyfrom 2 to 10 hours.

The compound (I_(−e)) can be produced by further placing the reactionproduct along with the compound (VII). The amount of the compound (VII)to be used ranges from about 1 to 10 mol and preferably from about 2 to5 mol relative to 1 mol of the raw material. It is advantageous to carryout this reaction without using a solvent or using an inert solvent inthe reaction. The solvent to be used is not particularly limited as longas the reaction proceeds, but for example, alcohols and organic acids ormixed solvents thereof are preferable. Generally, it is desirable tocarry out the reaction under ice cold conditions or at room temperatureor under reflux conditions by heating and preferably at a temperatureranging from 0° C. to 150° C. The reaction time generally ranges from0.1 to 10 hours and preferably from 0.5 to 5 hours. This process can becarried out by the method described in the Journal of HeterocyclicChemistry, 1981, 18, 333-334 or by a comparable method.

If the raw material compounds contain an amino group, a carboxyl group,a hydroxyl group as a substituent, in each reaction in the manufacturingmethods of said compounds (I-a), (I-b), (I-c), (I-d), (I-e), (I-f),(I-g), (I-h), (I-i), and (I-j), or salts thereof, and in each reactionin the synthesis of the raw material compounds, a protective group thatis generally used in peptide chemistry can be introduced into thesegroup. If preferable, the protective group is removed after the reactionto be able to obtain a target compound.

As a protective group for the amino group, for example, formyl and thefollowing group that can be respectively substituted can be used: C₁₋₁₀alkylcarbonyl (e.g., acetyl, ethylcarbonyl, etc.), phenylcarbonyl,C₁₋₁₀alkyl-oxycarbonyl (e.g., methoxycarbonyl, ethoxycarbonyl, etc.),phenyloxycarbonyl, C₇₋₁₀ aralkyl-carbonyl (e.g., benzylcarbonyl, etc.),trityl, phthaloyl, or N, N-dimethylaminomethylene. The substituents tobe used can include halogen (e.g., fluorine, chlorine, bromine, iodine,etc.), C₁₋₁₀ alkyl-carbonyl (e.g., methylcarbonyl, ethylcarbonyl,butylcarbonyl, etc.), nitro group and the like. The number ofsubstituents ranges from 1 to 3.

As a protective group for the carboxyl group, for example, the followinggroup that can be respectively substituted can be used: C₁₋₁₀ alkyl(e.g., methyl, ethyl, n-propyl, i-propyl, n-butyl, tert-butyl, etc.),phenyl, trityl, or silyl and the like. The substituents to be used caninclude halogen (e.g., fluorine, chlorine, bromine, iodine, etc.),formyl, C₁₋₁₀ alkyl-carbonyl (e.g., acetyl, ethylcarbonyl,butylcarbonyl, etc.), nitro groups and the like. The number ofsubstituents ranges from 1 to 3.

As a protective group for the hydroxyl group, for example, the followinggroup that can be respectively substituted can be used: C₁₋₁₀ alkyl(e.g., methyl, ethyl, n-propyl, i-propyl, n-butyl, tert-butyl, etc.),phenyl, C₇₋₁₀ aralkyl (e.g., benzyl, etc.), formyl, C₁₋₁₀ alkyl-carbonyl(e.g., acetyl, ethylcarbonyl, etc.), phenyloxycarbonyl, benzoyl, C₇₋₁₀aralkyl-carbonyl (e.g., benzylcarbonyl, etc.), pyranyl, furanyl, orsilyl and the like. The substituents to be used can include halogen(e.g., fluorine, chlorine, bromine, iodine, etc.), C₁₋₁₀ alkyl (e.g.,methyl, ethyl, n-propyl, etc.), phenyl, C₇₋₁₀ aralkyl (e.g., benzyl,etc.), nitro group and the like. The number of substituents ranges from1 to 4.

Further, as a method of removing the protective group, the known methodor a comparable method can be used. For example, a method of treatingwith acids, bases, reduction, UV-light, hydrazine, phenylhydrazine,sodium N-methyldithiocarbamate, tetrabutylammonium fluoride, palladiumacetate and the like can be used.

In each reaction in the manufacturing methods of said compounds (I-a),(I-b), (I-c), (I-d), (I-e), (I-f), (I-g), (I-h), (I-i), and (I-j), ortheir salts, and in each reaction in the synthesis of the raw materialcompounds, solvents that are generally known may be used during thereaction.

For example, the following generally known solvents can be used:

ethers such as tetrahydrofuran, diethylether, 1,2-dimethoxyethane,1,4-dioxane and the like;

esters such as ethyl acetate, butyl acetate and the like;

aromatic hydrocarbons such as benzene, toluene and the like;

aromatic heterocyclic compounds such as pyridine, lutidine and the like;

amides such as N, N-dimethylformamide, N-methylpyrrolidone and the like;

halogenated compounds such as chloroform, methylene chloride and thelike;

alcohols such as methanol, ethanol, 2-propanol, 2,2-dimethylethanol andthe like;

aliphatic hydrocarbon compounds such as hexane, heptane, petroleum etherand the like;

carboxylic acids such as formic acid, acetic acid and the like; andwater.

Further, the solvents used in the reaction can be used as a singlesolvent or as a solvent mixture of two kinds to 6 kinds.

Further, the reaction can be carried out in the presence of amines suchas triethylamine, N, N-diisopropylamine, pyridine, N-methylmorpholineand the like or bases such as sodium hydroxide, potassium carbonate andthe like. Alternatively, the reaction can be carried out in the presenceof an acid such as hydrochloric acid, sulfuric acid, acetic acid and thelike.

The compounds obtained by the aforementioned methods: (I-a), (I-b),(I-c), (I-d), (I-e), (I-f), (I-g), (I-h), (I-i), and (I-j) can beisolated or purified by the ordinary separation means such asrecrystallization, distillation, chromatography and the like. If thecompounds of the present invention: (I-a), (I-b), (I-c), (I-d), (I-e),(I-f), (I-g), (I-h), (I-i), and (I-j) are obtained in a free form, theycan be converted to their salts by the known methods or by a comparablemethod (e.g., neutralization, etc.), or in reverse, if they are obtainedin the salt form, they can be converted to a free form or other salts bythe known methods or by a comparable method. If the compound obtainedare racemates, they can be separated into a d-form and l-form by theordinary optical separation means.

The raw material compounds of the compounds (I-a), (I-b), (I-c), (I-d),(I-e), (I-f), (I-g), (I-h), (I-i), and (I-j) or salts thereof are notparticularly limited as long as there are no interference with thereaction. Examples of such salts are same as the salts of the compounds(I-a), (I-b), (I-c), (I-d), (I-e), (I-f), (I-g), (I-h), (I-i), and(I-j).

In any of the above mentioned manufacturing methods or processes, ifdesired, a compound (I_(o)) can be synthesized by further applying oneor combination of known reactions such as protection/deprotectionreactions, acylation reactions, alkylation reactions, hydrogenationreactions, oxidation reactions, reduction reactions, carbon chainextension reactions, substituent exchanging reactions, and so on.

If the target products are obtained in the free form by theaforementioned reactions, they can be converted to the correspondingsalts by the ordinary methods, or if they are obtained in the salt form,they can be converted to the free form or other salts by the ordinarymethods. The compound (I_(o)) obtained can be isolated from the reactionmixture and purified by the known means such as phase transfer,concentration, solvent extraction, fractional distillation,crystallization, recrystallization, chromatography and the like.

If the compound (I_(o)) is present as a configurational isomer,diastereomer, or conformer, if desired, they can be isolatedrespectively by the aforementioned isolation and purification means. Ifthe compound (I_(o)) is present as a racemate, it can be separated to ad-form and l-form by the ordinary optical separation means.

As in the case of the compound (I_(o)), a prodrug of the compound(I_(o)) can be used. The prodrug of the compound (I_(o)) is a compoundthat is converted to a compound (I_(o)) by reactions using enzymes orgastric acid under physiological conditions in vivo. Namely, it includesa compound that is converted to a compound (I_(o)) by enzymaticoxidation, reduction and hydrolysis or a compound that is converted to acompound (I_(o)) by hydrolysis using gastric acid.

Prodrugs of the compound (I_(o)) include compounds wherein an aminogroup in the compound (I_(o)) is acylated, alkylated or phosphorylated(e.g., the amino group in the compound (I_(o)) is eicosanoylated,alanylated, pentylaminocarbonylated, (5-methyl-2-oxo-1, 3-dioxolen-4-yl)methoxycarbonylated, tetrahydrofuranylated, pyrrolidylmethylated,pivaloyloxymethylated or tert-butylated); the hydroxyl group in thecompound (I_(o)) is acylated, alkylated, phosphorylated or borated(e.g., the hydroxyl group in the compound (I_(o)) is acetylated,palmitoylated, propanoylated, pivaloylated, succinylated, fumarylated,alanylated, dimethylaminomethylcarbonylated); the carboxyl group in thecompound (I_(o)) is esterified or amidated (e.g., the carboxyl group inthe compound (I_(o)) is ethyl-esterified, phenyl-esterified,carboxymethyl-esterified, dimethylaminomethyl-esterified,pivaloyloxymethyl-esterified, ethoxycarbonyloxyethyl-esterified,phthalidyl-esterified,(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl-esterified,cyclohexyloxycarbonylethyl-esterified, or methylamidated). Thesecompounds can be produced from the compound (I_(o)) by the knownmethods. Prodrugs of the compound (I_(o)) can be converted to thecompound (I_(o)) under the physiological conditions as described in“Development of Drugs” Vol. 7 Molecular Design published in 1990 byHirokawa Shoten, page 163 to 198.

The compound of the present invention has an excellent PDE10A inhibitoryactivity and is useful for the following diseases and symptoms inmammals (e.g., humans, cows, horses, dogs, cats, monkeys, mice, rats,etc. particularly in humans):

psychotic disorder (e.g., brief psychotic disorder, shared psychoticdisorder);

psychosis induced by alcohol, amphetamine, cannabis, cocaine,hallucinogens, obesity, inhalants, opioids, or phencyclidine;

delusional disorder;

anxiety disorder;

movement disorder;

mood disorder;

major depressive disorder;

a major depressive disorder superimposed on a psychotic disordercomprising a delusional disorder or schizophrenia;

major depressive episode of the mild, moderate or severe type;

manic or mixed mood episode;

hypomanic mood episode;

depressive episode with atypical features;

depressive episode with melancholic features;

depressive episode with catatonic features;

mood episode with postpartum onset;

post-stroke depression;

dysthymic disorder;

minor depressive disorder;

autism

drug addiction

neurodegenerative disorder;

neurodegeneration associated with cerebral trauma;

neurodegeneration associated with stroke;

neurodegeneration associated with cerebral infarct;

hypoglycemia-induced neurodegeneration;

neurodegeneration associated with epileptic seizure;

neurodegeneration associated with neurotoxin poisoning;

multi-system atrophy;

Alzheimer's disease;

dementia;

multi-infarct dementia;

alcoholic dementia or other drug-related dementia;

dementia associated with intracranial tumors or cerebral trauma;

dementia associated with Huntington's disease or Parkinson's disease;

AIDS-related dementia;

Fronto temperal dementia;

delirium;

amnestic disorder;

post-traumatic stress disorder;

mental retardation;

learning disorder (e.g., reading disorder, mathematics disorder, or adisorder of written expression);

attention-deficit/hyperactivity disorder;

age-related cognitive decline;

premenstrual dysphoric disorder;

post-psychotic depressive disorder of schizophrenia;

bipolar disorder comprising bipolar I disorder, bipolar II disorder;

cyclothymic disorder;

Parkinson's disease;

Huntington's disease;

paranoid;

schizophrenia (e.g., paranoid schizophrenia, disorganized schizophrenia,disorganized schizophrenia, catatonic schizophrenia, undifferentiatedschizophrenia, residual schizophrenia);

schizophreniform disorder;

schizoaffective disorder of the delusional type or the depressive type;

personality disorder of the paranoid type;

personality disorder of the schizoid type;

obesity;

metabolic syndrome;

non-insulin dependent diabetes (NIDDM);

glucose intolerance;

In particular, the compound of the present invention is useful forpreventing or treating schizophrenia.

Since the compound of the present invention demonstrates excellentmetabolic stability, superior therapeutic effects on the aforementioneddiseases are expected even at a low dosage.

The compound of the present invention can be administered safely, as itis, or in a dosage form which is manufactured according to a per seknown method for manufacturing pharmaceutical formulations (e.g.,methods described in Japanese Pharmacopoeia) such as tablets (inclusiveof sugar coated tablet, film coated tablet, sublingual tablet, orallydisintegrable tablet, and buccal), pills, powders, granules, capsules(inclusive of soft capsule, and microcapsule), troches, syrups, liquiddosage forms, emulsions, controlled-release preparations (e.g.,quick-release preparation, sustained-release preparation,sustained-release microcapsule), aerosols, films (e.g., orallydisintegrable film, adhesive film for application to oral-cavitymucosa), injections (e.g., subcutaneous injection, intravenousinjection, intramuscular injection, intraperitoneal injection), dripinfusion, percutaneous absorbent, ointment, lotion, patch, suppositories(e.g., rectal suppository, vaginal suppository), pellets, transnasalpreparations, pulmonary preparations (inhalant), eye drops and the like,in an oral or parenteral route (e.g., intravenous, intramuscular,subcutaneous, intraorgan, intranasal, intradermal, ophthalmicinstillation, intracerebral, intrarectal, intravaginal, intraperitoneal,directly to lesion).

Here, as a pharmaceutical acceptable carrier, common organic orinorganic carrier substances are used as formulation raw materials.Carriers are added as vehicles, lubricants, binders and disintegrants inthe solid formulations; and as solubilizing agents, suspending agents,isotonization agents, buffers and soothing agents in the liquidformulations. If desired, formulation additives such as antiseptics,antioxidants, colorants, sweeteners, etc. can be used.

Favorable examples of the vehicles are as follows: lactose, sucrose,D-mannitol, D-sorbitol, starch, α-starch, dextrin, crystallinecellulose, low-substituted hydroxypropyl cellulose, sodiumcarboxymethylcellulose, gum Arabic, pullulan, light silicic anhydride,synthetic aluminum silicate and magnesium metasilicic aluminate.

Favorable examples of the lubricants include magnesium stearate, calciumstearate, talc and colloidal silica.

Favorable examples of the binders are as follows: α-starch, sucrose,gelatin, gum Arabic, methylcellulose, carboxymethylcellulose, sodiumcarboxymethylcellulose, crystalline cellulose, sucrose, D-mannitol,trehalose, dextrin, pullulan, hydroxypropylcellulose, hydroxypropylmethyl cellulose and polyvinylpyrrolidone.

Favorable examples of the disintegrants are as follows: lactose,sucrose, starch, carboxymethylcellulose, calcium carboxymethylcellulose,croscarmellose sodium, sodium carboxymethyl starch, light silicicanhydride and low-substituted hydroxypropylcellulose.

Favorable examples of the solvents are as follows: water for injection,physiological saline, Linger solution, alcohol, propylene glycol,polyethylene glycol, sesame oil, corn oil, olive oil and cottonseed oil.

Favorable examples of the solubilizing agents are as follows:polyethylene glycol, propylene glycol, D-mannitol, trehalose,benzylbenzoate, ethanol, tris-aminomethane, cholesterol,triethanolamine, sodium carbonate, sodium citrate, sodium salicylate andsodium acetate.

Favorable examples of the suspending agents are as follows: surfactantssuch as stearyl triethanolamine, sodium lauryl sulfate, laurylaminopropionic acid, lecithin, benzalkonium chloride, benzethonium chloride,and glycerin monostearate; hydrophilic polymers such as polyvinylalcohol, polyvinyl pyrrolidone, sodium carboxymethylcellulose,methylcellulose, hydroxymethyl cellulose, hydroxyethyl cellulose andhydroxypropyl cellulose; polysorbates, and polyoxyethylene-hardenedcastor oil.

Favorable examples of the isotonization agents include sodium chloride,glycerin, D-mannitol, D-sorbitol and glucose.

Favorable examples of the buffers include buffer solutions ofphosphates, acetates, carbonates and citrates.

Favorable examples of the soothing agents include benzyl alcohol.

Favorable examples of antiseptics include para-oxybenzoic acid esters,chlorobutanol, benzyl alcohol, phenethyl alcohol, dehydroacetic acid andsorbic acid.

Favorable examples of antioxidants include sulfites and ascorbates.

Favorable examples of the colorants include water soluble edible tardyes (e.g., edible dyes such as Food Red No. 2 and No. 3, Food YellowNo. 4 and No. 5, Food Blue No. 1 and 2); water insoluble lake dyes(e.g., aluminum salts of the aforementioned water soluble edible tardyes), natural dyes (e.g., β-carotene, chlorophyll, red iron oxide).

Favorable examples of the sweeteners include sodium saccharin,dipotassium glycyrrhizate, aspartame and stevia.

The medical compositions of the present invention can be manufactured bythe common methods in the field of formulation technology, for example,methods listed in the Japanese pharmacopoeia. Specific manufacturingmethods for formulations are described in detail below.

The content of the compound of the present invention in the medicalcompositions of the present invention varies based on the dosage forms,dosages of the compound of the present invention, etc. For example, thecontent approximately ranges from 0.01 to 100 wt % and preferably from0.1 to 95 wt % relative to the entire amount of the composition.

The dosage of the compound of the present invention depends uponinjection targets, administration routes, target diseases, symptoms,etc. For example, in the case of oral administration in patients withschizophrenia (adults, bodyweight of approximately 60 kg), generally asingle dose ranges from approximately 0.1 to 20 mg/kg bodyweight,preferably from approximately 0.2 to 10 mg/kg bodyweight, furtherpreferably from approximately 0.5 to 10 mg/kg bodyweight, and thisdosage is preferably administered once daily or several times daily(e.g., 3 times).

The compounds can be administered as the sole active agent or incombination with other pharmaceutical agents such as other agents usedin the treatment of psychosis, especially schizophrenia and bipolardisorder, obsessive-compulsive disorder, major depression, Parkinson'sdisease, Alzheimer's disease, cognitive impairment and/or memory loss,e.g., nicotinic α7 agonists, nicotinic α7 partial agonists, nicotinic α7positive allosteric modulators, PDE2 inhibitors, PDE4 inhibitors, PDE5inhibitors, other PDE inhibitors, calcium channel blockers, muscarinicm1 and m2 modulators, adenosine receptor modulators, ampakines, Glycinetransporter 1 inhibitors, NMDA-R modulators, mGluR modulators, dopaminemodulators, serotonin modulators, selective serotonin reuptakeinhibitors, serotonin and norepinephrine reuptake inhibitors,norepinephrine and dopamine reuptake inhibitors, triple reuptakeinhibitors, cannabinoid modulators, and cholinesterase inhibitors (e.g.,donepezil, rivastigimine, and galantamine). In such combinations, eachactive ingredient can be administered either in accordance with theirusual dosage range or a dose below their usual dosage range, and can beadministered either simultaneously or sequentially.

Drugs suitable in combination with the compounds of the presentinvention include, but are not limited to, other suitable schizophreniadrugs such as Haldol, Clozaril, Zyprexa, Risperdal, Abilify, Geodon,Invega, and Seroquel; bipolar disorder drug, including, but not limitedto, Lithium, Zyprexa, Abilify, and Depakote; Parkinson's disease drugs,including, but not limited to, Levodopa, Parlodel, Permax, Mirapex,Tasmar, Kemadrin, Artane, and Cogentin; agents used in the treatment ofmaj or depression, including, but not limited to, Elavil, Tofranil,Norpramin, Pamelor, Paxil, Prozac, Zoloft, Wellbutrin, Lexapro, Remeron,Effexor, Cymbalta; agents used in the treatment of Alzheimer's disease,including, but not limited to, Reminyl, Cognex, Aricept, Exelon,Akatinol, Neotropin, Eldepryl, Estrogen and Cliquinol; agents used inthe treatment of dementia, including, but not limited to, Mellaril,Haldol, Risperdal, Cognex, Aricept, and Exelon; agents used in thetreatment of epilepsy, including, but not limited to, Dilantin, Luminal,Tegretol, Depakote, Depakene, Zarontin, Neurontin, Barbita, Solfeton andFelbatol; agents used in the treatment of multiple sclerosis, including,but not limited to, Detrol, Ditropan XL, OxyContin, Betaseron, Avonex,Azathioprine, Trexall and Copaxone; agents used in the treatment ofHuntington's disease, including, but not limited to, Elavil, Tofranil,Norpramin, Pamelor, Paxil, Prozac, Zoloft, Nitoman, Haldol, Thorazine,Mellaril, Dogmatil, Seroquel, Clozaril, and Risperdal; agents useful inthe treatment of diabetes, including, but not limited to, PPAR ligands(e.g. agonists, antagonists, such as Rosiglitazone, Troglitazone andPioglitazone), insulin secretagogues (e.g., sulfonylurea drugs, such asGlyburide, Glimepiride, Chlopropamide, Tolbutamide, and Glipizide, andnon-sulfonyl secretagogues), α-glucosidase inhibitors (such as Acarbose,Miglitol, and Voglibose), insulin sensitizers (such as the PPAR-γagonists, e.g., the glitazones; biguanides, PTP-1B inhibitors, DPP-IVinhibitors, and 11beta-HSD inhibitors), hepatic glucose output loweringcompounds (such as glucagon antagonists and metformin, e.g., Glucophageand Glucophage XR), insulin and insulin derivatives (both long and shortacting forms and formulations of insulin); and antiobesity drugs,including, but not limited to, β-3 agonists, CB-1 agonists, neuropeptideY5 inhibitors, Ciliary Neurotrophic Factor and derivatives (e.g.,Axokine), appetite suppressants (e.g., Sibutramine), and lipaseinhibitors (e.g., Orlistat).

The form of administration of concomitant drugs with the compound of thepresent invention is not particularly limited and is acceptable as longas the compound of the present invention is combined with concomitantdrugs at the time of administration. Examples of such forms ofadministration are as follows:

-   -   (1) Administration of a single formula obtained simultaneous        formulation of the compound of the present invention with a        concomitant drug,    -   (2) Simultaneous administration via the same administration        route for two kinds of formulas obtained by independent        formulations of the compound of the present invention and a        concomitant drug,    -   (3) Administrations at different times via the same        administration route for two kings of formulas obtained by        independent formulations of the compound of the present        invention and a concomitant drug,    -   (4) Simultaneous administration via different administration        routes for two kinds of formulas obtained by independent        formulations of the compound of the present invention and a        concomitant drug,    -   (5) Administrations at different times via different        administration routes for two kinds of formulas obtained by        independent formulations of the compound of the present        invention and a concomitant drug. (For example, administration        in the order of the composition of the present invention a        concomitant drug, or administration in the reversed order).        These forms of administration are summarized below and        abbreviated as a concomitant agent of the present invention.

When administering the concomitant agent of the present invention, aconcomitant drug and the compound of the present invention can beadministered at the same time, but the compound of the present inventioncan be administered after a concomitant drug is administered or afterthe compound of the present invention is administered, a concomitantdrug can be administered. When administering at different times, thetime difference depends upon the active ingredients to be administered,drug forms and methods of administration. For example, when aconcomitant drug is administered first, the compound of the presentinvention can be administered within 1 min. to 3 days, preferably within10 min. to 1 day and more preferably within 15 min. to 1 hour after theconcomitant drug is administered. However, if the compound of thepresent invention is administered first, a concomitant drug can beadministered within 1 min. to 1 day, preferably within 10 min. to 6hours and more preferably within 15 min. to 1 hour after the compound ofthe present invention is administered.

If there are no problems with side effects of the concomitant drugs, anydosages can be set. A daily dosage as a concomitant drug depends upondosages, administration subjects, administration routes, targetdiseases, symptoms, etc. For example, in the case of oral administrationin patients with schizophrenia (adults, bodyweight of approximately 60kg), a normal daily dosage ranges from about 0.1 to 20 mg/kg bodyweight,preferably from about 0.2 to 10 mg/kg bodyweight and more preferablyfrom about 0.5 to 10 mg/kg bodyweight. It is preferable that this dosageis administered once daily to several times daily (e.g., 3 times).

If the compound of the present invention is used in combination with aconcomitant drug, the respective dosages can be reduced within a saferange with consideration of the opposite effects of the respectivedrugs.

The concomitant agent of the present invention exhibits low toxicity.For example, the compound of the present invention or(and) theaforementioned concomitant drug can be combined with a pharmaceuticallyacceptable carrier according to the known method to prepare a medicalcomposition such as tablets (including sugar-coated tablets andfilm-coated tablets), powder agents, granular agents, capsules(including soft capsules), liquids, injection solutions, suppositories,sustained-release agents, etc. These compositions can be administeredsafely orally or non-orally (e.g., including local, rectal and venousroutes).

The pharmaceutically acceptable carriers that can be used formanufacturing the concomitant agent of the present invention can be thesame as those used in the medical composition of the present inventionas mentioned above.

A mixing ratio between the compound of the present invention and aconcomitant drug in the concomitant agent of the present invention canbe selected appropriately based on the administration subjects,administration routes and diseases.

The aforementioned concomitant drugs can be combined at an appropriateproportion if two or more drugs are combined.

A dosage of the concomitant drug can be selected appropriately based onthe dosages used clinically. In addition, a mixing ratio between thecompound of the present invention and a concomitant drug can be selectedappropriately based on the administration subjects, administrationroutes, target diseases, symptoms, combinations, etc. For example, ifthe administration subject is humans, a concomitant drug can be used inan amount ranging from 0.01 to 100 parts by weight relative to 1 part byweight of the compound of the present invention.

For example, the content of the compound of the present invention in theconcomitant agent of the present invention varies with the drug form offormulations. Generally, it is present in a range from about 0.01 to99.9 wt %, preferably from about 0.1 to 50 wt % and more preferably fromabout 0.5 to 20 wt % relative to the entire formula.

The content of a concomitant drug in the concomitant agent of thepresent invention varies with the drug form of formulations. Generallyit is present in a range from about 0.01 to 99.9 wt %, preferably fromabout 0.1 to 50 wt % and more preferably from about 0.5 to 20 wt %relative to the entire formula.

The content of an additive such as carriers in the concomitant agent ofthe present invention varies with the drug form of formulations.Generally it is present in a range from about 1 to 99.99 wt % andpreferably from about 10 to 90 wt % relative to the entire formula.

When the compound of the present invention and a concomitant drug areformulated independently, the same contents can be applied.

Since the dosages may fluctuate under various conditions as mentionedabove, a dosage less than the aforementioned dosages may be sufficientor it may be necessary to administer at a dosage exceeding the range.

EXAMPLES

The present invention will be explained in detail below with referenceto the reference examples, embodiments, formulation examples andexperimental examples. Since these are simply examples, the presentinvention will not be limited to these examples and the presentinvention can be modified in the range not deviating from the scope ofthe present invention.

In the following reference examples and embodiments, “room temperature”indicates generally approximately 10° C. to 35° C. As for %, % in termsof yields indicates mol/mol %, % in terms of the solvent used forchromatography indicates vol %, and % in other cases indicates wt %. Inthe proton NMR spectrum, OH and NH protons that cannot be identified dueto broad bands are not recorded in the data. Kiesselgel 60 by Merck &Co., Inc. was used in silica gel chromatography and Chromatorex NH byFuji Silysia Chemical Ltd. was used in basic silica gel chromatography.

Abbreviations used in other sections of the text imply the followingmeanings.

s: singlet

d: doublet

dd: doublet of doublets

dt: doublet of triplets

t: triplet

tt: triplet of triplets

td: triplet of doublets

q: quartet

septet: septet

m: multiplet

br: broad

J: coupling constant

Hz: hertz

CDCl₃: deuterochloroform

DMSO-d₆: deutero-dimethyl sulfoxide

¹H-NMR: proton nuclear magnetic resonance

HPLC: high performance liquid chromatography

THF: tetrahydrofuran

DMF: N, N-dimethylformamide

DMSO: dimethylsulfoxide

NMP: N-methylpyrrolidone

HOBt: 1-hydroxybenzotriazole

WSC: 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride

HATU: hexafluorophosphate2-(7-aza-1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium

DMTMM: 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholiniumchloride n-hydrate

DBU: 1,8-diazabicyclo[5.4.0]-7-undecene

LC-MS: liquid chromatography/mass spectroscopy

ESI: electrospray ionization

CDI: 1, 1′-carbonyldiimidazole

dba: dibenzylideneacetone

DIBAL: diisobutylaluminium hydride

DME: 1,2-dimethoxyethane

DPPA: diphenylphosphoryl azide

HMPA: hexamethylphosphoric triamide

selectfluor: 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octanebis(tetrafluoroborate)

TEA: triethylamine

TFA: trifluoroacetic acid

TMSCl: trimethylsilyl chloride

Xantphos: 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene

Rt: retention time

All reagents and solvents were of commercial quality and used withoutfurther purification. Column chromatography was performed using Mercksilica gel 60 (230-400 mesh). The compounds and/or intermediates werepurified by preparative high performance liquid chromatography (prep.HPLC) using a Gilson High through Put purification system.

The columns were reversed phase YMC CombiPrep Pro C18, S-5 μm, 19×50 mm.A gradient elution was used (flow rate 20 mL/min), typically startingwith 5% acetonitrile/95% water and progressing to 100% acetonitrile overa Period of 7 min. All solvents contained 0.1% trifluoroacetic acid(TFA).

Massspectrometric analysis was performed according to liquidchromatography/mass spectroscopy (LCMS) methods. The method employed aWaters LC-MS System (Agilent HP1100 HPLC and a Micromass ZMD massspectrometer for the LCMS instrument, a CAPCELL PAK C18, UG120, S-3 μm,1.5×35 mm for the chromatography column, and a solvent system that was a5-95% gradient of acetonitrile in water with 0.04% TFA over a 3.60 minperiod (flow rate 0.5 mL/min molecular weight range 200-800; coneVoltage 20 V; column temperature 40° C.). All masses were reported asthose of the protonated parent ions.

Reference Example 13-{[3-(Trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione

3-(Trifluoromethyl)aniline (34.6 g, 215 mmol) was dissolved in a mixtureof concentrated hydrochloric acid (64 mL) and water (64 mL). To theresulting mixture was added dropwise at 0° C. a solution of sodiumnitrite (16.6 g, 240 mmol) in water (100 mL). The mixture was stirredfor 1 h at 0° C. To the resulting diazonium salt solution was addeddropwise a solution of pentane-2,4-dione (22.0 g, 220 mmol) and sodiumacetate (52.5 g, 640 mmol) in ethanol (225 mL) and water (80 mL) at roomtemperature. The mixture was stirred for 18 h at room temperature with amechanical stirrer. The orange precipitate was filtered off and washedwith water (150 mL×3), 50 percent aqueous ethanol (100 mL×2), andn-hexane (100 mL), and then dried in vacuo at 50° C. for 5 h affording52.7 g (90%) of3-{[3-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione as an orangesolid.

¹H NMR (400 MHz, CDCl₃): δ ppm 2.52 (s, 3H), 2.63 (s, 3H), 7.45-7.44 (m,1H), 7.58-7.51 (m, 2H), 7.66 (s, 1H), 14.68 (s, 1H). LC-MS (MH⁺) 273.10.

Reference Example 23-[3-(Dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of 3-{[3-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione(4.3 g, 15.8 mmol) and N,N-dimethylformamide dimethylacetal (40 mL) washeated in an oil bath at 120° C. for 5 h. The solvent was removed underreduced pressure to give quantitative yield of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a black oil, which was used as is in the next step without furtherpurification.

LC-MS (MH⁺) 338.16.

Reference Example 33-{[4-(Trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione

To a solution of 4-(trifluoromethyl)aniline (1090 mg, 6.80 mmol) in 5 mLof water and 5 mL of concentrated hydrochloride solution, sodium nitrite(563 mg, 8.16 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (1670 mg, 20.40 mmol)and acetylacetone (748 mg, 7.48 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-{[4-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (580 mg, 31%).

¹H NMR (300 MHz, CDCl₃): δ ppm 2.51 (s, 3H), 2.62 (s, 3H), 7.44 (d,J=8.7 Hz, 2H), 7.69 (d, J=8.7 Hz, 2H), 14.59 (s, 1H).

Reference Example 43-[3-(Dimethylamino)prop-2-enoyl]-1-[4-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

3-{[4-(Trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (580 mg, 2.13mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-[4-(trifluoromethyl)phenyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 5 3-[(3-Chlorophenyl)hydrazono]pentane-2,4-dione

To a solution of 3-chloroaniline (1000 mg, 7.87 mmol) in 5 mL of waterand 5 mL of concentrated hydrochloride solution, sodium nitrite (652 mg,9.45 mmol) in 4 mL of water was added dropwise at 0° C., and the mixturewas stirred at 0° C. for 1 h. Then to the reaction mixture was addeddropwise a solution of sodium acetate (1936 mg, 23.61 mmol) andacetylacetone (866 mg, 8.66 mmol) in 10 mL of ethanol and 6 mL of water.The mixture was stirred at room temperature overnight, filtered, washedwith water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(3-chlorophenyl)hydrazono]pentane-2,4-dione (450 mg, 24%).

LCMS: m/z=239 [35Cl, M⁺+H].

Reference Example 61-(3-Chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-[(3-Chlorophenyl)hydrazono]pentane-2,4-dione (450 mg, 1.89 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude1-(3-chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 7 3-[(2-Methoxyphenyl)hydrazono]pentane-2,4-dione

To a solution of 2-methoxyaniline (1000 mg, 8.13 mmol) in 10 mL ofacetic acid and 2 mL of concentrated hydrochloride solution, sodiumnitrite (673 mg, 9.76 mmol) in 4 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a solution of sodium acetate (2000 mg, 24.39mmol) and acetylacetone (1057 mg, 10.57 mmol) in 10 mL of ethanol and 6mL of water. The mixture was stirred at room temperature overnight,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive 3-[(2-methoxyphenyl)hydrazono]pentane-2,4-dione (1500 mg, 79%).

LCMS: m/z=235 [M⁺+H].

Reference Example 83-[3-(Dimethylamino)prop-2-enoyl]-1-(2-methoxyphenyl)pyridazin-4(1H)-one

3-[(2-Methoxyphenyl)hydrazono]pentane-2,4-dione (500 mg, 2.14 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(2-methoxyphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 9 3-[(4-Methoxyphenyl)hydrazono]pentane-2,4-dione

To a solution of 4-methoxyaniline (1000 mg, 8.13 mmol) in 10 mL ofacetic acid and 2 mL of concentrated hydrochloride solution, sodiumnitrite (673 mg, 9.76 mmol) in 4 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a solution of sodium acetate (2000 mg, 24.39mmol) and acetylacetone (1057 mg, 10.57 mmol) in 10 mL of ethanol and 6mL of water. The mixture was stirred at room temperature overnight,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive 3-[(4-methoxyphenyl)hydrazono]pentane-2,4-dione (950 mg, 50%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.50 (s, 3H), 2.62 (s, 3H), 3.86 (s, 3H),6.96-6.98 (m, 2H), 7.38-7.41 (m, 2H), 14.99 (s, 1H).

Reference Example 103-[3-(Dimethylamino)prop-2-enoyl]-1-(4-methoxyphenyl)pyridazin-4(1H)-one

3-[(4-Methoxyphenyl)hydrazono]pentane-2,4-dione (500 mg, 2.14 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(4-methoxyphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 11 3-[(3-Fluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 3-fluoroaniline (1000 mg, 9.00 mmol) in 5 mL of waterand 5 mL of concentrated hydrochloride solution, sodium nitrite (746 mg,10.80 mmol) in 4 mL of water was added dropwise at 0° C., and themixture was stirred at 0° C. for 1 h. Then to the reaction mixture wasadded dropwise a solution of sodium acetate (2220 mg, 27.00 mmol) andacetylacetone (990 mg, 9.90 mmol) in 10 mL of ethanol and 6 mL of water.The mixture was stirred at room temperature overnight, filtered, washedwith water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(3-fluorophenyl)hydrazono]pentane-2,4-dione (650 mg, 33%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.50 (s, 3H), 2.62 (s, 3H), 6.90 (dt,J=2.4, 8.0 Hz, 1H), 7.11 (dd, J=1.6, 8.0 Hz, 1H), 7.21 (td, J=2.4, 10.0Hz, 1H), 7.34-7.39 (m, 1H), 14.61 (s, 1H).

Reference Example 123-[3-(Dimethylamino)prop-2-enoyl]-1-(3-fluorophenyl)pyridazin-4(1H)-one

3-[(3-Fluorophenyl)hydrazono]pentane-2,4-dione (650 mg, 2.93 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(3-fluorophenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 13 3-[(2-Fluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 2-fluoroaniline (1000 mg, 9.00 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(746 mg, 10.80 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (2220 mg, 27.00 mmol)and acetylacetone (990 mg, 9.90 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(2-fluorophenyl)hydrazono]pentane-2,4-dione (1280 mg, 64%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.51 (s, 3H), 2.62 (s, 3H), 7.14-7.24 (m,3H), 7.77 (d, J=8.0 Hz, 1H), 14.71 (s, 1H).

Reference Example 143-[3-(Dimethylamino)prop-2-enoyl]-1-(2-fluorophenyl)pyridazin-4(1H)-one

3-[(2-Fluorophenyl)hydrazono]pentane-2,4-dione (600 mg, 2.70 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(2-fluorophenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 15 3-[(4-Fluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 4-fluoroaniline (1000 mg, 9.00 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(746 mg, 10.80 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (2220 mg, 27.00 mmol)and acetylacetone (990 mg, 9.90 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(4-fluorophenyl)hydrazono]pentane-2,4-dione (1200 mg, 60%).

¹H NMR (300 MHz, CDCl₃): δ ppm 2.49 (s, 3H), 2.61 (s, 3H), 7.09-7.15 (m,2H), 7.37-7.41 (m, 2H), 14.85 (s, 1H).

Reference Example 163-[3-(Dimethylamino)prop-2-enoyl]-1-(4-fluorophenyl)pyridazin-4(1H)-one

3-[(4-Fluorophenyl)hydrazono]pentane-2,4-dione (650 mg, 2.93 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(4-fluorophenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 17 3-[(4-Chlorophenyl)hydrazono]pentane-2,4-dione

To a solution of 4-chloroaniline (1000 mg, 7.87 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(652 mg, 9.45 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (1936 mg, 23.61 mmol)and acetylacetone (1023 mg, 10.23 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(4-chlorophenyl)hydrazono]pentane-2,4-dione (1680 mg, 90%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.49 (s, 3H), 2.61 (s, 3H), 7.33-7.39 (m,4H), 14.70 (s, 1H).

Reference Example 181-(4-Chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-[(4-Chlorophenyl)hydrazono]pentane-2,4-dione (600 mg, 2.52 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 hours, then concentrated underreduced pressure to give crude1-(4-chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 19 3-[(2-Methylphenyl)hydrazono]pentane-2,4-dione

To a solution of 2-methylaniline (1000 mg, 9.34 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(774 mg, 11.21 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (2299 mg, 28.04 mmol)and acetylacetone (1215 mg, 12.15 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(2-methylphenyl)hydrazono]pentane-2,4-dione (1000 mg, 49%). LCMS:m/z=219 [M⁺+H].

Reference Example 203-[3-(Dimethylamino)prop-2-enoyl]-1-(2-methylphenyl)pyridazin-4(1H)-one

3-[(2-Methylphenyl)hydrazono]pentane-2,4-dione (1000 mg, 4.59 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(2-methylphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 21 3-[(3-Methylphenyl)hydrazono]pentane-2,4-dione

To a solution of 3-methylaniline (1000 mg, 9.34 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(774 mg, 11.21 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (2299 mg, 28.04 mmol)and acetylacetone (1215 mg, 12.15 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(3-methylphenyl)hydrazono]pentane-2,4-dione (500 mg, yield 24%).LCMS: m/z=219 [M⁺+H].

Reference Example 223-[3-(Dimethylamino)prop-2-enoyl]-1-(3-methylphenyl)pyridazin-4(1H)-one

3-[(3-Methylphenyl)hydrazono]pentane-2,4-dione (500 mg, 2.29 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(3-methylphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 23 3-[(3-Methoxyphenyl)hydrazono]pentane-2,4-dione

To a solution of 3-methoxyaniline (1000 mg, 8.13 mmol) in 10 mL ofacetic acid and 2 mL of concentrated hydrochloride solution, sodiumnitrite (673 mg, 9.76 mmol) in 4 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a solution of sodium acetate (2000 mg, 24.39mmol) and acetylacetone (1057 mg, 10.57 mmol) in 10 mL of ethanol and 6mL of water. The mixture was stirred at room temperature overnight,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive 3-[(3-methoxyphenyl)hydrazono]pentane-2,4-dione (840 mg, 44%).LCMS: m/z=235 [M⁺+H].

Reference Example 243-[3-(Dimethylamino)prop-2-enoyl]-1-(3-methoxyphenyl)pyridazin-4(1H)-one

3-[(3-Methoxyphenyl)hydrazono]pentane-2,4-dione (500 mg, 2.14 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(3-methoxyphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 253-{[2-(Trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione

To a solution of 2-(trifluoromethyl)aniline (1.09 g, 6.80 mmol) in 5 mLof water and 5 mL of concentrated hydrochloride solution, sodium nitrite(563 mg, 8.16 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (1.67 g, 20.40 mmol) andacetylacetone (748 mg, 7.48 mmol) in 10 mL of ethanol and 6 mL of water.The mixture was stirred at room temperature overnight, filtered, washedwith water, EtOH/H₂O (1:1) and hexane, and dried to give3-{[2-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (634 mg, 33%).

¹H NMR (300 MHz, CDCl₃): δ ppm 2.52 (s, 3H), 2.63 (s, 3H), 7.24-7.29 (m,1H), 7.60-7.66 (m, 2H), 7.96 (8.4 Hz, 1H), 15.06 (s, 1H).

Reference Example 263-[3-(Dimethylamino)prop-2-enoyl]-1-[2-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

3-{[2-(Trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (634 mg, 2.33mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-[2-(trifluoromethyl)phenyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 273-[(4-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione

To a solution of 4-morpholin-4-ylaniline (1000 mg, 5.62 mmol) in 10 mLof acetic acid and 2 mL of concentrated hydrochloride solution, sodiumnitrite (465 mg, 6.74 mmol) in 4 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a solution of sodium acetate (2764 mg, 33.71mmol) and acetylacetone (730 mg, 7.30 mmol) in 10 mL of ethanol and 6 mLof water. The mixture was stirred at room temperature overnight,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive 3-[(4-morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione (900 mg,55%).

LCMS: m/z=290 [M⁺+H].

Reference Example 283-[3-(Dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

3-[(4-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione (900 mg, 3.11mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 29 3-(Phenylhydrazono)pentane-2,4-dione

To a solution of aniline (2000 mg, 21.50 mmol) in 30 mL of acetic acidand 5 mL of concentrated hydrochloride solution, sodium nitrite (1780mg, 25.80 mmol) in 8 mL of water was added dropwise at 0° C., and themixture was stirred at 0° C. for 1 h. Then to the reaction mixture wasadded dropwise a solution of sodium acetate (5290 mg, 64.50 mmol) andacetylacetone (2795 mg, 27.95 mmol) in 20 mL of ethanol and 12 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-(phenylhydrazono)pentane-2,4-dione (2955 mg, 67%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.50 (s, 3H), 2.61 (s, 3H), 7.21 (dd,J=8.0, 4.4 Hz, 1H), 7.41 (d, J=4.4 Hz, 4H), 14.74 (s, 1H).

Reference Example 303-[3-(Dimethylamino)prop-2-enoyl]-1-phenylpyridazin-4(1H)-one

3-(Phenylhydrazono)pentane-2,4-dione (470 mg, 2.30 mmol) was dissolvedin 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA), and themixture was refluxed for 4 h, then concentrated under reduced pressureto give crude3-[3-(dimethylamino)prop-2-enoyl]-1-phenylpyridazin-4(1H)-one which wasused to the next step without further purification.

¹H NMR of the crude product (400 MHz, DMSO-d₆): δ ppm 2.84 (s, 3H), 3.11(s, 3H), 5.50 (br, 1H), 6.55 (d, J=8.0 Hz, 1H), 7.43-7.46 (m, 1H), 7.57(t, J=7.6 Hz, 2H), 7.70 (d, J=8.0 Hz, 2H), 8.81 (d, J=8.0 Hz, 1H).

Reference Example 31 3-[(4-Methylphenyl)hydrazono]pentane-2,4-dione

To a solution of 4-methylaniline (1000 mg, 9.34 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(774 mg, 11.21 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (2299 mg, 28.04 mmol)and acetylacetone (1215 mg, 12.15 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(4-methylphenyl)hydrazono]pentane-2,4-dione (480 mg, 24%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.36 (s, 3H), 2.49 (s, 3H), 2.60 (s, 3H),7.21 (d, J=8.0 Hz, 2H), 7.32 (d, J=8.0 Hz, 2H), 14.82 (s, 1H).

Reference Example 323-[3-(Dimethylamino)prop-2-enoyl]-1-(4-methylphenyl)pyridazin-4(1H)-one

3-[(4-Methylphenyl)hydrazono]pentane-2,4-dione (462 mg, 2.12 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(4-methylphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

¹H NMR of the crude product (400 MHz, DMSO-d₆): δ ppm 2.38 (s, 3H), 2.84(s, 3H), 3.10 (s, 3H), 6.53 (d, J=8.0 Hz, 1H), 7.37 (d, J=8.0 Hz, 2H),7.58 (d, J=8.0 Hz, 2H), 8.76 (d, J=8.0 Hz, 1H).

Reference Example 333-{[2-(Difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

To a solution of 2-(difluoromethoxy)aniline (1000 mg, 6.25 mmol) in 15mL of acetic acid and 2.5 mL of concentrated hydrochloride solution,sodium nitrite (518 mg, 7.50 mmol) in 4 mL of water was added dropwiseat 0° C., and the mixture was stirred at 0° C. for 1 h. Then to thereaction mixture was added dropwise a solution of sodium acetate (1538mg, 18.75 mmol) and acetylacetone (812 mg, 8.12 mmol) in 10 mL ofethanol and 6 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1:1) and hexane, anddried to give 3-{[2-(difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione(1590 mg, 94%).

LCMS: m/z=271 [M⁺+H].

Reference Example 341-[2-(Difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-{[2-(Difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (500 mg, 1.85mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 hours, then concentratedunder reduced pressure to give crude1-[2-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 353-{[3-(Difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

To a solution of 3-(difluoromethoxy)aniline (1000 mg, 6.25 mmol) in 10mL of acetic acid and 2 mL of concentrated hydrochloride solution,sodium nitrite (518 mg, 7.50 mmol) in 4 mL of water was added dropwiseat 0° C., and the mixture was stirred at 0° C. for 1 h. Then to thereaction mixture was added dropwise a solution of sodium acetate (1538mg, 18.75 mmol) and acetylacetone (812 mg, 8.12 mmol) in 10 mL ofethanol and 6 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1:1) and hexane, anddried to give 3-{[3-(difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione(1500 mg, 89%).

LCMS: m/z=271 [M⁺+H].

Reference Example 361-[3-(Difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-{[3-(Difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (800 mg, 2.96mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude1-[3-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 373-{[4-(Difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

To a solution of 4-(difluoromethoxy)aniline (1000 mg, 6.25 mmol) in 10mL of acetic acid and 2 mL of concentrated hydrochloride solution,sodium nitrite (518 mg, 7.50 mmol) in 4 mL of water was added dropwiseat 0° C., and the mixture was stirred at 0° C. for 1 h. Then to thereaction mixture was added dropwise a solution of sodium acetate (1538mg, 18.75 mmol) and acetylacetone (812 mg, 8.12 mmol) in 10 mL ofethanol and 6 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1:1) and hexane, anddried to give 3-{[4-(difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione(1400 mg, yield 82%).

LCMS: m/z=271 [M⁺+H].

Reference Example 381-[4-(Difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-{[4-(Difluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (600 mg, 2.22mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude1-[4-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 393-[(2-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione

To a solution of 2-morpholin-4-ylaniline (1000 mg, 5.62 mmol) in 10 mLof acetic acid and 2 mL of concentrated hydrochloride solution, sodiumnitrite (465 mg, 6.74 mmol) in 4 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a solution of sodium acetate (2764 mg, 33.71mmol) and acetylacetone (730 mg, 7.30 mmol) in 10 mL of ethanol and 6 mLof water. The mixture was stirred at room temperature overnight,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive 3-[(2-morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione (1000 mg,62%).

LCMS: m/z=290 [M⁺+H].

Reference Example 403-[3-(Dimethylamino)prop-2-enoyl]-1-(2-morpholin-4-ylphenyl)pyridazin-4(1H)-one

3-[(2-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione (1000 mg, 2.46mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(2-morpholin-4-ylphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 41 3-(Pyridin-3-ylhydrazono)pentane-2,4-dione

To 3-aminopyridine (564 mg, 6.00 mmol) were added 4 mL of concentratedsulfuric acid and 1.2 mL of water at 0° C., and the mixture was stirredat room temperature until it was clear. To the reaction mixture wasadded a solution of sodium nitrite (414 mg, 6.00 mmol) in water (1.2 mL)at 0° C. The mixture was stirred for several min (>15 min). The solutionof diazonium salt was poured into the solution of 2,4-pentanedione (600mg, 6.00 mmol) and potassium acetate (18.0 g, 180 mmol) in ethanol (120mL) at 0° C. The mixture was stirred at 0° C. for 30 min and at roomtemperature for 30 min. The reaction mixture was added to 120 mL ofsaturated Na₂CO₃ aqueous solution. The mixture was extracted withdichloromethane, washed with water and brine, dried over Na₂SO₄, andconcentrated under reduced pressure to give3-(pyridin-3-ylhydrazono)pentane-2,4-dione (242 mg, yield 20%).

LCMS: m/z=206 [M⁺+H].

Reference Example 423-[3-(Dimethylamino)prop-2-enoyl]-1-pyridin-3-ylpyridazin-4(1H)-one

3-(Pyridin-3-ylhydrazono)pentane-2,4-dione (200 mg, 0.98 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-pyridin-3-ylpyridazin-4(1H)-onewhich was used to the next step without further purification.

¹H NMR of the crude product (400 MHz, CDCl₃): δ ppm 2.90 (s, 3H), 3.15(s, 3H), 5.64 (d, J=11.6 Hz, 1H), 6.74 (d, J=8.4 Hz, 1H), 7.45-7.48 (m,1H), 8.00-8.03 (m, 1H), 8.20 (d, J=8.0 Hz, 1H), 8.65-8.66 (m, 1H), 8.88(d, J=2.8 Hz, 1H).

Reference Example 43 3-(Pyridin-4-ylhydrazono)pentane-2,4-dione

4-Aminopyridine (470 mg, 5.00 mmol) was added to a solution of 3 mL ofphosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C. When themixture reached to room temperature it was cooled to −6° C. and solidsodium nitrite (350 mg, 5.00 mmol) was added during 10 min. Small piecesof ice (50 g) were added into the solution. The mixture was added at 0°C. to a suspension of corresponding 2,4-pentanedione (500 mg, 5.00 mmol)and potassium acetate (20 g) in ethanol (250 mL). The solution wasstirred for 15 min, added to 250 mL of saturated Na₂CO₃ aqueoussolution, extracted with dichloromethane, washed with water and brine,dried over Na₂SO₄, and concentrated under reduced pressure to give3-(pyridin-4-ylhydrazono)pentane-2,4-dione (149 mg, yield 14%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.52 (s, 3H), 2.62 (s, 3H), 7.27-7.29 (m,2H), 8.59-8.61 (m, 2H), 14.23 (s, 1H).

Reference Example 443-[3-(Dimethylamino)prop-2-enoyl]-1-pyridin-4-ylpyridazin-4(1H)-one

3-(Pyridin-4-ylhydrazono)pentane-2,4-dione (120 mg, 0.58 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-pyridin-4-ylpyridazin-4(1H)-onewhich was used to the next step without further purification.

¹H NMR of the crude product (400 MHz, CDCl₃): δ ppm 2.92 (s, 3H), 3.16(s, 3H), 5.56-5.58 (m, 1H), 6.73 (d, J=8.0 Hz, 1H), 7.59 (dd, J=4.8, 1.6Hz, 2H), 8.30 (d, J=8.0 Hz, 1H), 8.74 (dd, J=4.8, 1.6 Hz, 2H).

Reference Example 45 3-[(2-Chlorophenyl)hydrazono]pentane-2,4-dione

To a solution of 2-chloroaniline (1000 mg, 7.87 mmol) in 10 mL of aceticacid and 2 mL of concentrated hydrochloride solution, sodium nitrite(652 mg, 9.45 mmol) in 4 mL of water was added dropwise at 0° C., andthe mixture was stirred at 0° C. for 1 h. Then to the reaction mixturewas added dropwise a solution of sodium acetate (1940 mg, 23.62 mmol)and acetylacetone (1024 mg, 10.24 mmol) in 10 mL of ethanol and 6 mL ofwater. The mixture was stirred at room temperature overnight, filtered,washed with water, EtOH/H₂O (1:1) and hexane, and dried to give3-[(2-chlorophenyl)hydrazono]pentane-2,4-dione (860 mg, 46%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.52 (s, 3H), 2.64 (s, 3H), 7.11-7.15 (m,1H), 7.34-7.37 (m, 1H), 7.42 (dd, J=8.0, 1.2 Hz, 1H), 7.81 (dd, J=8.0,1.2 Hz, 1H), 14.88 (s, 1H).

Reference Example 461-(2-Chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-[(2-Chlorophenyl)hydrazono]pentane-2,4-dione (500 mg, 2.10 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal (DMF-DMA),and the mixture was refluxed for 4 h, then concentrated under reducedpressure to give crude1-(2-chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

¹H NMR of the crude product (400 MHz, CDCl₃): δ ppm 2.90 (s, 3H), 3.12(s, 3H), 5.56-5.59 (m, 1H), 6.67 (d, J=8.0 Hz, 1H), 7.42-7.45 (m, 2H),7.52-7.57 (m, 2H), 7.91 (d, J=8.0 Hz, 1H).

Reference Example 473-{[3-(Methylsulfanyl)phenyl]hydrazono}pentane-2,4-dione

A solution of 3-(methylsulfanyl)aniline (13.9 g, 100 mmol) inhydrochloric acid (6 N, 100 mL) was cooled with an ice brine bath andtreated with a solution of sodium nitrite (8.38 g, 121 mmol) in water(25 mL) dropwise to keep the temperature between −5° C. and 5° C. The insitu formed diazonium solution was quickly added to a mixture of2,4-pentanedione (10.2 g, 102 mmol) and sodium acetate (150 g, 183 mmol)in ethanol (170 mL) and water (60 mL) cooled to below 0° C. Afterstirring at 0° C. for 30 min, the suspension was filtered, washed withwater (40 mL) and evaporated with toluene to afford3-{[3-(methylsulfanyl)phenyl]hydrazono}pentane-2,4-dione (23.10 g, 92%)as a yellow-red solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.43 (s, 6H), 2.47 (s, 3H), 7.04-7.06(m, 1H), 7.31-7.36 (m, 2H), 7.46 (s, 1H), 13.80 (br s, 1H); APCI MS m/z251 [M+H]⁺.

Reference Example 483-[3-(Dimethylamino)prop-2-enoyl]-1-[3-(methylsulfanyl)phenyl]pyridazin-4(1H)-one

A mixture of 3-{[3-(methylsulfanyl)phenyl]hydrazono}pentane-2,4-dione(14.9 g, 59.6 mmol) in N,N-dimethylformamide dimethylacetal (70 mL) wasstirred at 125° C. for 2.5 h. After this time, the reaction was directlyconcentrated and then dissolved in methanol (80.0 mL). Afterconcentration, the crude product was purified by flash chromatography(silica gel, methylene chloride to 95:5 methylene chloride/methanol) toafford3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(methylsulfanyl)phenyl]pyridazin-4(1H)-one(16.3 g, 87%) as a yellow-brown solid.

¹H NMR (500 MHz, DMSO-d₆) δ 2.54 (s, 3H), 2.83 (s, 3H), 3.09 (s, 3H),5.23 (br s, 1H), 6.53 (d, J=8.0 Hz, 1H), 7.29-7.32 (m, 1H), 7.43-7.53(m, 4H), 8.81 (d, J=8.0 Hz, 1H); APCI MS m/z 316 [M+H]⁺.

Reference Example 491-[3-(Methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one

A mixture of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(methylsulfanyl)phenyl]pyridazin-4(1H)-one(3.69 g, 11.7 mmol) in methanol (80 mL) was treated with phenylhydrazine(2.66 g, 24.6 mmol) and the resulting mixture was stirred at reflux for8 h. After this time, the reaction was directly concentrated to removemethanol and then dissolved in methylene chloride (100 mL). The solutionwas washed with 2 N hydrochloride (60 mL), water (60 mL), and brine (60mL). After concentration, the crude product was purified by flashchromatography (silica gel, methylene chloride to 95:5 methylenechloride/methanol) afforded1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one(2.72 g, 65%) in a regiomeric ratio of about 1:1 as a white solid.

¹H NMR for 2 isomers (500 MHz, DMSO-d₆) δ ppm 6.63 (d, J=8.0 Hz, 1H),6.66 (d, J=7.9 Hz, 1H), 6.82-6.85 (m, 1H), 7.05 (s, 1H), 7.19-7.22 (m,2H), 7.29 (t, J=8.0 Hz, 1H), 7.34-7.39 (m, 5H), 7.42 (d, J=7.1 Hz, 1H),7.45-7.49 (m, 2H), 7.50-7.56 (m, 3H), 7.59 (d, J=9.3 Hz, 1H), 7.68 (s,1H), 7.82 (d, J=1.7 Hz, 1H), 7.92 (d, J=7.8 Hz, 2H), 8.59 (d, J=2.4 Hz,1H), 8.84 (d, J=8.0 Hz, 1H), 8.89 (d, J=7.9 Hz, 1H); APCI MS m/z 361[M+H]⁺.

Reference Example 50 3-[(3-Hydroxyphenyl)hydrazono]pentane-2,4-dione

A solution of 3-aminophenol (5.16 g, 47.3 mmol) in tetrafluoroboric acid(30 mL, 50% in water) was cooled with ice brine bath and treated withsodium nitrite (3.92 g, 56.8 mmol) in water (18 mL) dropwise to keep thebath temperature between −5° C. and 5° C. The in situ formed diazoniumsolution was quickly added to a mixture of 2,4-pentanedione (4.73 g,47.3 mmol) and sodium acetate (100 g, 73.5 mmol) in ethanol (80 mL) andwater (30 mL) below 0° C. After stirring at 0° C. for 30 min, thesuspension was filtered, washed with water (70 mL) and evaporated withtoluene to afford 3-[(3-hydroxyphenyl)hydrazono]pentane-2,4-dione (5.85g, 56%) as a brick-red solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.42 (s, 6H), 3.44 (br s, 1H), 6.58-6.60(m, 1H), 6.90-6.93 (m, 1H), 6.99 (d, J=2.1 Hz, 1H), 7.15-7.18 (m, 1H);ESI MS m/z 221 [M+H]⁺.

Reference Example 513-[3-(Dimethylamino)prop-2-enoyl]-1-(3-hydroxyphenyl)pyridazin-4(1H)-one

A mixture of 3-[(3-hydroxyphenyl)hydrazono]pentane-2,4-dione (2.02 g,9.18 mmol) in N,N-dimethylformamide dimethylacetal (20 mL) was stirredat 100° C. for 1 h. After this time, the reaction was directlyconcentrated and then dissolved in methanol (60 mL). After evaporationwith silica gel, the crude product was purified by flash chromatography(silica gel, methylene chloride to 92:8 methylene chloride/methanol) toafford3-[3-(dimethylamino)prop-2-enoyl]-1-(3-hydroxyphenyl)pyridazin-4(1H)-one(1.72 g, 66%) as a brown-red solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.83 (s, 3H), 3.09 (s, 3H), 5.21-5.23(m, 1H), 6.50 (d, J=8.0 Hz, 1H), 6.79-6.82 (m, 1H), 7.08-7.11 (m, 2H),7.33 (t, J=8.1 Hz, 1H), 8.74 (d, J=8.0 Hz, 1H), 9.93 (s, 1H); ESI MS m/z286 [M+H]⁺.

Reference Example 521-(3-Hydroxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-[3-(dimethylamino)prop-2-enoyl]-1-(3-hydroxyphenyl)pyridazin-4(1H)-one(0.481 g, 1.69 mmol) in methanol (10 mL) was treated withphenylhydrazine (0.462 g, 4.28 mmol) and the resulting mixture wasstirred at reflux for 14 h. After this time, the reaction was directlyconcentrated to remove methanol and then dissolved in methylene chloride(60 mL). The solution was washed with water (60 mL), and brine (20 mL).After concentrated with silica gel, chromatography (silica, methylenechloride to 1:19 methanol/methylene chloride) afforded1-(3-hydroxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(0.360 g, 65%) as a brown-yellow solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 6.63 (d, J=7.8 Hz, 1H), 6.85 (d, J=9.0Hz, 1H), 7.21-7.23 (m, 2H), 7.35-7.39 (m, 3H), 7.52-7.56 (m, 2H), 7.92(d, J=7.9 Hz, 2H), 8.59 (d, J=2.3 Hz, 1H), 8.81 (d, J=7.8 Hz, 1H), 10.0(s, 1H); ESI MS m/z 331 [M+H]⁺.

Reference Example 533-(1-Phenyl-1H-pyrazol-5-yl)-1-(3-sulfanylphenyl)pyridazin-4(1H)-one and3-(1-phenyl-1H-pyrazol-3-yl)-1-(3-sulfanylphenyl)pyridazin-4(1H)-one

A solution of1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one(0.300 g, 0.83 mmol) and sodium t-butylthiolate (0.295 g, 2.63 mmol) inDMF (6 mL) was heated at 170° C. in a sealed tube for 2.5 days. Afterthat time, the reaction was cooled to room temperature and diluted withwater (60 mL). Aqueous HCl (1 N, 2 mL, 2 mmol) was added and thereaction extracted with ethyl acetate (2×80 mL). The combined organicphases were washed with aqueous 5% LiCl solution (100 mL) and saturatedNaCl aqueous solution (80 mL). The organics were dried (MgSO₄) andconcentrated to yield the mixture of the title compounds as a brown gum(0.325 g). LCMS analysis of the reaction product indicated that 2isomers of the thiol product were produced in ≈1.5:1 ratio. The crudeproduct was used in the following reaction without further purificationor characterization.

Reference Example 541-[3-(1H-Benzimidazol-2-ylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(1H-benzimidazol-2-ylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one

A solution of the crude mixture of3-(1-phenyl-1H-pyrazol-5-yl)-1-(3-sulfanylphenyl)pyridazin-4(1H)-one and3-(1-phenyl-1H-pyrazol-3-yl)-1-(3-sulfanylphenyl)pyridazin-4(1H)-one(0.325 g, 0.94 mmol), 2-chlorobenzimidazole (0.195 g, 1.27 mmol), andpotassium carbonate (0.234 g, 1.70 mmol) in N-methylpyrrolidone (8.0 mL)was heated at 170° C. in a sealed tube for 24 hours. After that time,the reaction was cooled to room temperature and diluted with water (50mL). Aqueous HCl (2 N, 0.800 mL, 1.60 mmol) was added and the reactionextracted with ethyl acetate (3×60 mL). The combined organic phases werewashed with aqueous 5% LiCl solution (100 mL) and saturated NaCl aqueoussolution (100 mL). The organics were dried (MgSO₄) and concentrated to abrown solid (0.312 g). The crude product was used in the followingreaction without further purification or characterization.

Reference Example 55 Methyl3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}butanoate

A slurry of 3-(trifluoromethyl)aniline (16.12 g, 100 mmol) in 6 N HCl(100 mL) was cooled to 0° C. and treated dropwise with a solution ofsodium nitrite (8.33 g, 121 mmol) in water (20 mL). The resulting paleyellow solution was poured into a slurry of methyl acetoacetate (11.62g, 100 mmol) and sodium acetate (150 g) in ethanol (170 mL), pre-cooledto 0° C. The resulting orange slurry was stirred for 10 min. After thattime, the product was collected by filtration and washed with water (500mL). The crude material was dissolved in ethyl acetate (250 mL) anddried (MgSO₄). The product crystallized upon concentration of the ethylacetate to give 19.997 g (69%) of methyl3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}butanoate as light yellowcrystals.

¹H NMR (300 MHz, CDCl₃) shows a mixture of isomers. Major isomer 6 ppm2.62 (s, 3H), 3.90 (s, 3H), 7.37-7.45 (m, 1H), 7.46-7.54 (m, 1H), 7.58(s, 1H), 7.67 (s, 1H), 14.76 (br s, 1H); Minor isomer 6 ppm 2.52 (s,3H), 3.93 (s, 3H), 7.37-7.45 (m, 1H), 7.46-7.54 (m, 2H), 7.56 (s, 1H),12.81 (br s, 1H); APCI MS m/z 289 [C₁₂H₁₁F₃N₂O₃+H]⁺.

Reference Example 56 Methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate

A solution of methyl3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}butanoate (15.20 g, 52.7mmol) in N,N-dimethylformamide dimethylacetal (150 mL) was heated atreflux for 2 h. After that time, the reaction was cooled to roomtemperature and then on an ice water bath. The product was collected byfiltration to give methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(13.7 g, 87%) as pale yellow crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 4.00 (s, 3H), 6.80 (d, J=8.1 Hz, 1H),7.61-7.76 (m, 2H), 7.76-7.91 (m, 2H), 8.28 (d, J=8.1 Hz, 1H); APCI MSm/z 299 [C₁₃H₉F₃N₂O₃+H]⁺.

Reference Example 574-Oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbohydrazide

A solution of methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(1.019 g, 3.42 mmol) and hydrazine monohydrate (0.3 mL, 6.19 mmol) inethanol (10 mL) was heated under microwave conditions for 10 min at 120°C. After that time, the reaction was cooled to room temperature and theproduct was collected by filtration and washed with cold ethanol to give4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbohydrazide(0.607 g, 60%) as bright orange crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 4.34 (d, J=4.6 Hz, 2H), 6.93 (d, J=7.8 Hz,1H), 7.66-7.79 (m, 2H), 7.86-8.00 (m, 2H), 8.36 (d, J=7.8 Hz, 1H), 10.98(br s, 1H); APCI MS m/z 299 [C₁₂H₉F₃N₄O₂+H]⁺.

Reference Example 584-Oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

A solution of methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(1.007 g, 3.38 mmol) in ammonia (7 N in MeOH, 12 mL, 84 mmol) was heatedunder microwave heating conditions at 100° C. for 5 min. After that timethe reaction was cooled to room temperature and concentrated to give ayellow solid. This was recrystallized from EtOAc to give 0.613 g (64%)of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamideas colorless crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 6.46 (br s, 1H), 6.94 (d, J=7.8 Hz, 1H),7.59-7.80 (m, 2H), 7.84-8.01 (m, 2H), 8.38 (d, J=7.8 Hz, 1H), 9.68 (brs, 1H); APCI MS m/z 284 [M+H]⁺.

Reference Example 59N-[(Dimethylamino)methylidene]-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

A slurry of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(0.54 g, 1.91 mmol) in N,N-dimethylformamide dimethylacetal (10 mL) washeated under microwave heating conditions at 130° C. for 15 min. Afterthat time the reaction was cooled on an ice water bath and the resultingcrystals collected by filtration and washed with hexanes to give 0.491 g(76%) ofN-[(dimethylamino)methylidene]-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamideas off white crystals. ¹H NMR (300 MHz, CDCl₃) δ ppm 3.16 (s, 3H), 3.22(s, 3H), 6.72 (d, J=8.1 Hz, 1H), 7.57-7.71 (m, 2H), 7.74-7.85 (m, 1H),7.89 (s, 1H), 8.25 (d, J=8.1 Hz, 1H), 8.70 (s, 1H).

Reference Example 604-Oxo-N-phenyl-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

A solution of aniline (0.360 mL, 3.95 mmol) in methylene chloride (10mL) was cooled on an ice water bath then treated with a solution oftrimethyl aluminum (2 M in toluene, 2.0 mL, 4.0 mmol). After theaddition was complete, the reaction was allowed to warm to roomtemperature and stirred for 30 min. At that point, methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(0.595 g, 2.00 mmol) was added and the reaction was heated at reflux for18 h. After that time, the reaction was cooled to room temperature andcarefully quenched with HCl aqueous solution (1 N, 5 mL). The organiclayer was separated and the aqueous layer was extracted with methylenechloride (3×10 mL). The combined organic extracts were washed withsaturated NaHCO₃ aqueous solution (50 mL) and brine (50 mL), dried(MgSO₄), and concentrated. The residue was recrystallized from ethylacetate/hexanes to give 0.214 g (30%) of4-oxo-N-phenyl-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamideas yellow crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 6.96 (d, J=7.7 Hz, 1H), 7.16 (t, J=7.4 Hz,1H), 7.37 (t, J=7.9 Hz, 2H), 7.61-7.85 (m, 4H), 7.88-8.01 (m, 2H), 8.42(d, J=7.8 Hz, 1H), 12.19 (br s, 1H); APCI MS m/z 360 [M+H]⁺; mp 181-182°C.

Reference Example 613-[1H-Benzotriazol-1-yl(phenylimino)methyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of4-oxo-N-phenyl-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(0.153 g, 0.426 mmol), 1H-benzo[d][1,2,3]triazole (0.201 g, 1.69 mmol)and thionyl chloride (0.06 mL, 0.82 mmol) in methylene chloride (2 mL)was heated under microwave heating conditions at 80 watts of power for10 min. After that time, the reaction was concentrated and the crudeproduct purified by flash column chromatography (silica gel, hexanes toethyl acetate) to give 0.114 g (58%) of3-[1H-benzotriazol-1-yl(phenylimino)methyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale red solid that was used without further characterization.

Reference Example 623-[(4-Piperidin-1-ylphenyl)hydrazono]pentane-2,4-dione

4-Piperidin-1-ylaniline (510 mg, 2.90 mmol) was added to a solution of 3mL of phosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C. Whenthe mixture reached to room temperature it was cooled to −6° C. andsolid sodium nitrite (200 mg, 2.90 mmol) was added during 10 min. Smallpieces of ice (50 g) were added into the solution. The mixture was addedat 0° C. to a suspension of corresponding 2,4-pentanedione (290 mg, 2.90mmol) and potassium acetate (20 g) in ethanol (250 mL). The solution wasstirred for 15 min, added to 250 mL of saturated Na₂CO₃ aqueoussolution, extracted with dichloromethane, washed with water and brine,dried over Na₂SO₄, and concentrated under reduced pressure to give3-[(4-piperidin-1-ylphenyl)hydrazono]pentane-2,4-dione (570 mg, yield68%).

LCMS: m/z=288 [M⁺+H].

Reference Example 633-[3-(Dimethylamino)prop-2-enoyl]-1-(4-piperidin-1-ylphenyl)pyridazin-4(1H)-one

3-[(4-Piperidin-1-ylphenyl)hydrazono]pentane-2,4-dione (570 mg, 1.99mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-(4-piperidin-1-ylphenyl)pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 64 3-[(4-Cyclohexylphenyl)hydrazono]pentane-2,4-dione

To a solution of 4-cyclohexylaniline (500 mg, 2.86 mmol) in 10 mL ofacetic acid and 2 mL of concentrated hydrochloride solution, sodiumnitrite (237 mg, 3.43 mmol) in 4 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a solution of sodium acetate (703 mg, 8.58mmol) and acetylacetone (372 mg, 3.72 mmol) in 10 mL of ethanol and 6 mLof water. The mixture was stirred at room temperature overnight,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive 3-[(4-cyclohexylphenyl)hydrazono]pentane-2,4-dione (420 mg, 51%).

¹H NMR (400 MHz, CDCl₃): δ ppm 1.24-1.27 (m, 2H), 1.38-1.43 (m, 4H),1.85-1.87 (m, 4H), 2.49-2.52 (m, 4H), 2.60 (s, 3H), 7.25 (d, J=8.4 Hz,2H), 7.35 (d, J=8.8 Hz, 2H), 14.81 (s, 1H).

Reference Example 651-(4-Cyclohexylphenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one

3-[(4-Cyclohexylphenyl)hydrazono]pentane-2,4-dione (406 mg, 1.42 mmol)was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude1-(4-cyclohexylphenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

¹H NMR of the crude product (400 MHz, CDCl₃): δ ppm 1.25-1.28 (m, 2H),1.39-1.44 (m, 4H), 1.86-1.88 (m, 4H), 2.52-2.54 (m, 1H), 2.90 (s, 3H),3.13 (s, 3H), 5.62-5.64 (m, 1H), 6.71 (d, J=7.6 Hz, 1H), 7.32 (d, J=8.8Hz, 2H), 7.49 (d, J=8.8 Hz, 2H), 8.17 (d, J=8.0 Hz, 1H).

Reference Example 664-[2-(1-Acetyl-2-oxopropylidene)hydrazino]benzonitrile

4-Aminobenzonitrile (500 mg, 4.24 mmol) was added to a solution of 3 mLof phosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C. Whenthe mixture reached to room temperature it was cooled to −6° C. andsolid sodium nitrite (292 mg, 4.24 mmol) was added during 10 min. Smallpieces of ice (50 g) were added into the solution. The mixture was addedat 0° C. to a suspension of corresponding 2,4-pentanedione (424 mg, 4.24mmol) and potassium acetate (20 g) in ethanol (250 mL). The solution wasstirred for 15 min, added to 250 mL of saturated Na₂CO₃ aqueoussolution, extracted with dichloromethane, washed with water and brine,dried over Na₂SO₄, and concentrated under reduced pressure to give4-[2-(1-acetyl-2-oxopropylidene)hydrazino]benzonitrile (280 mg, 29%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.51 (s, 3H), 2.63 (s, 3H), 7.47 (dd,J=7.2, 1.6 Hz, 2H), 7.70 (dd, J=7.2, 1.6 Hz, 2H), 14.51 (s, 1H).

Reference Example 674-{3-[3-(Dimethylamino)prop-2-enoyl]-4-oxopyridazin-1(4H)-yl}benzonitrile

4-[2-(1-Acetyl-2-oxopropylidene)hydrazino]benzonitrile (266 mg, 1.16mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude4-{3-[3-(dimethylamino)prop-2-enoyl]-4-oxopyridazin-1(4H)-yl}benzonitrile which was used to the next step without furtherpurification.

¹H NMR of the crude product (400 MHz, CDCl₃): δ ppm 2.96 (s, 3H), 3.20(s, 3H), 6.13 (d, J=12.4 Hz, 1H), 7.35 (d, J=8.8 Hz, 2H), 7.62 (d, J=8.8Hz, 2H), 7.83 (d, J=12.0 Hz, 1H).

Reference Example 683-{[4-(Methylsulfonyl)phenyl]hydrazono}pentane-2,4-dione

4-(Methylsulfonyl)aniline (500 mg, 2.92 mmol) was added to a solution of3 mL of phosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C.When the mixture reached to room temperature it was cooled to −6° C. andsolid sodium nitrite (201 mg, 2.92 mmol) was added during 10 min. Smallpieces of ice (50 g) were added into the solution. The mixture was addedat 0° C. to a suspension of corresponding 2,4-pentanedione (292 mg, 2.92mmol) and potassium acetate (20 g) in ethanol (250 mL). The solution wasstirred for 15 min, added to 250 mL of saturated Na₂CO₃ aqueoussolution, extracted with dichloromethane, washed with water and brine,dried over Na₂SO₄, and concentrated under reduced pressure to give3-{[4-(methylsulfonyl)phenyl]hydrazono}pentane-2,4-dione (780 mg, 95%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.52 (s, 3H), 2.63 (s, 3H), 3.08 (s, 3H),7.54 (dd, J=7.2, 2.0 Hz, 2H), 7.98 (dd, J=7.2, 2.0 Hz, 2H), 14.78 (s,1H).

Reference Example 693-[3-(Dimethylamino)prop-2-enoyl]-1-[4-(methylsulfonyl)phenyl]pyridazin-4(1H)-one

3-{[4-(Methylsulfonyl)phenyl]hydrazono}pentane-2,4-dione (500 mg, 1.77mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-[4-(methylsulfonyl)phenyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 703-{[4-(Morpholin-4-ylsulfonyl)phenyl]hydrazono}pentane-2,4-dione

4-(Morpholin-4-ylsulfonyl)aniline (300 mg, 1.24 mmol) was added to asolution of 3 mL of phosphoric acid (85%) and 2 mL of nitric acid (65%)at −6° C. When the mixture reached to room temperature it was cooled to−6° C. and solid sodium nitrite (85 mg, 1.24 mmol) was added during 10min. Small pieces of ice (50 g) were added into the solution. Themixture was added at 0° C. to a suspension of corresponding2,4-pentanedione (124 mg, 1.24 mmol) and potassium acetate (20 g) inethanol (250 mL). The solution was stirred for 15 min, added to 250 mLof a saturated solution of Na₂CO₃, extracted with dichloromethane,washed with water and brine, dried over Na₂SO₄, and concentrated underreduced pressure to give3-{[4-(morpholin-4-ylsulfonyl)phenyl]hydrazono}pentane-2,4-dione (375mg, 86%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.53 (s, 3H), 2.64 (s, 3H), 3.03 (t,J=4.8 Hz, 4H), 3.76 (t, J=4.8 Hz, 4H), 7.54 (dd, J=7.2, 2.0 Hz, 2H),7.80 (d, J=8.8 Hz, 2H), 14.56 (s, 1H).

Reference Example 713-[3-(Dimethylamino)prop-2-enoyl]-1-[4-(morpholin-4-ylsulfonyl)phenyl]pyridazin-4(1H)-one

3-{[4-(Morpholin-4-ylsulfonyl)phenyl]hydrazono}pentane-2,4-dione (300mg, 0.85 mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethylacetal (DMF-DMA), and the mixture was refluxed for 4 h, thenconcentrated under reduced pressure to give crude3-[3-(dimethylamino)prop-2-enoyl]-1-[4-(morpholin-4-ylsulfonyl)phenyl]pyridazin-4(1H)-onewhich was used to the next step without further purification.

Reference Example 72 4-[2-(1-Acetyl-2-oxopropylidene)hydrazino]benzamide

4-Aminobenzamide (1000 mg, 7.36 mmol) was added to a solution of 6 mL ofphosphoric acid (85%) and 4 mL of nitric acid (65%) at −6° C. When themixture reached to room temperature it was cooled to −6° C. and solidsodium nitrite (508 mg, 7.36 mmol) was added during 10 min. Small piecesof ice (100 g) were added into the solution. The mixture was added at 0°C. to a suspension of corresponding 2,4-pentanedione (736 mg, 7.36 mmol)and potassium acetate (40 g) in ethanol (400 mL). The solution wasstirred for 15 min, added to 250 mL of saturated Na₂CO₃ aqueoussolution, extracted with dichloromethane, washed with water and brine,dried over Na₂SO₄, and concentrated under reduced pressure to give4-[2-(1-acetyl-2-oxopropylidene)hydrazino]benzamide (460 mg, 25%).

¹H NMR (400 MHz, CDCl₃): δ ppm 2.52 (s, 3H), 2.62 (s, 3H), 7.46 (d,J=8.4 Hz, 2H), 7.88 (d, J=8.4 Hz, 2H), 14.62 (s, 1H).

Reference Example 734-{3-[3-(Dimethylamino)prop-2-enoyl]-4-oxopyridazin-1(4H)-yl}benzamide

4-[2-(1-Acetyl-2-oxopropylidene)hydrazino]benzamide (540 mg, 2.19 mmol)was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal(DMF-DMA), and the mixture was refluxed for 4 h, then concentrated underreduced pressure to give crude4-{3-[3-(dimethylamino)prop-2-enoyl]-4-oxopyridazin-1(4H)-yl}benzamidewhich was used to the next step without further purification.

¹H NMR of the crude product (400 MHz, CDCl₃): δ ppm 2.91 (s, 3H), 3.14(s, 3H), 5.60-5.62 (m, 1H), 6.73 (d, J=8.0 Hz, 1H), 7.65 (d, J=8.8 Hz,2H), 8.31 (d, J=8.0 Hz, 1H), 8.40 (d, J=9.2 Hz, 2H), 8.67 (s, 1H).

Reference Example 74 Methyl3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}pentanoate

A slurry of 3-(trifluoromethyl)aniline (8.03 g, 50 mmol) in 6 N HCl (50mL) was cooled to 0° C. and treated dropwise with a solution of sodiumnitrite (4.10 g, 60 mmol) in water (10 mL). The resulting pale yellowsolution was poured into a suspension of methyl propionylacetate (6.50g, 50 mmol) and sodium acetate (24.00 g, 292 mmol) in ethanol (80 mL),pre-cooled to 0° C. The resulting yellow/orange slurry was stirred for30 min. The product was collected by filtration and washed with water(100 mL). The crude material was dissolved in ethyl acetate (100 mL) anddried (Na₂SO₄). The product crystallized upon concentration of the ethylacetate to give (14.00 g, 93%) of methyl3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}pentanoate as ayellow/orange solid.

¹H NMR (500 MHz, CDCl₃) shows a mixture of isomers. Major isomer 6 ppm1.18 (t, J=7.5 Hz, 3H), 2.96 (q, J=7.5 Hz, 2H), 3.92 (s, 3H), 7.39-7.42(m, 1H), 7.48-7.55 (m, 2H), 7.56 (s, 1H), 12.75 (br s, 1H); Minor isomer6 ppm 1.15 (t, J=7.5 Hz, 3H), 3.04 (q, J=7.5, 2H), 3.90 (s, 3H),7.39-7.42 (m, 1H), 7.48-7.55 (m, 2H), 7.67 (s, 1H), 14.76 (br s, 1H);ESI MS m/z 303 [M+H]⁺.

Reference Example 75 Methyl5-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate

A solution of methyl3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}pentanoate (4.00 g, 13.2mmol) in N,N-dimethylformamide dimethylacetal (33 mL) was heated atreflux for 2.5 hours. After that time, the reaction was cooled to roomtemperature and the resulting solid was collected by filtration andwashed with a small amount of hexanes to give methyl5-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(3.55 g, 87%) as a pale yellow solid.

¹H NMR (500 MHz, CDCl₃) δ ppm 2.19 (s, 3H), 4.00 (s, 3H), 7.65-7.71 (m,2H), 7.81-7.85 (m, 2H), 8.20 (s, 1H); APCI MS m/z 313 [M+H]⁺.

Reference Example 76 N-Methoxy-N,5-dimethyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

To a stirred suspension of N,O-dimethylhydroxylamine hydrochloride(0.468 g, 4.8 mmol) in dichloromethane (5 mL) was addedtrimethylaluminum (2.4 mL, 4.8 mmol, 2 M solution in toluene) dropwiseat 0° C. Following addition, the suspension was stirred at 0° C. for 10min then at room temperature for 30 min to provide a homogenoussolution. The flask was then re-cooled in an ice bath. In a separateflask, methyl5-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(0.500 g, 1.6 mmol) was dissolved in dichloromethane (5 mL) and addeddropwise and allowed to stir for 2 h. The reaction was quenched withwater (5 mL) and 2 N HCl aqueous solution (2 mL). The layers wereseparated and the aqueous layer was extracted with dichloromethane (2×10mL). The combined organic extracts were washed with brine (20 mL), dried(Na₂SO₄), filtered and concentrated to provide N-methoxy-N,5-dimethyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(0.535 g, 98%) as a yellow solid.

¹H NMR (500 MHz, CDCl₃) δ ppm 2.18 (s, 3H), 3.41 (s, 3H), 3.68 (s, 3H),7.63-7.70 (m, 2H), 7.80-7.90 (m, 2H), 8.21 (s, 1H); APCI MS m/z 342[M+H]⁺.

Reference Example 773-Acetyl-5-methyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution ofN-methoxy-N,5-dimethyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(0.535 g, 1.6 mmol) in THF (10 mL) at −78° C. was added methylmagnesiumbromide (1.1 mL, 3.2 mmol, 3 M in diethyl ether). The reaction wasstirred at that temperature for 1 h then quenched with saturatedammonium chloride aqueous solution (5 mL) then water (2 mL) with slowwarming to room temperature. The reaction mixture was diluted with ethylacetate (20 mL) and the layers were separated. The aqueous layer wasextracted with ethyl acetate (2×10 mL) and the combined organic extractsare washed with 1 N HCl aqueous solution (15 mL), brine (15 mL), dried(Na₂SO₄), filtered and concentrated to provide3-acetyl-5-methyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.463 g, 98%) as a light yellow solid.

¹H NMR (500 MHz, CDCl₃) δ ppm 2.19 (s, 3H), 2.69 (s, 3H), 7.67-7.72 (m,2H), 7.82-7.85 (m, 2H), 8.21 (s, 1H); APCI MS m/z 297 [M+H]⁺.

Reference Example 783-[3-(Dimethylamino)prop-2-enoyl]-5-methyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A microwave vial containing3-acetyl-5-methyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.363 g, 1.2 mmol) and N,N-dimethylformamide dimethylacetal (2.5 mL)was heated at 120° C. for 20 min. The crude material was concentratedand purified by flash column chromatography (silica gel; methylenechloride to 1:9 methanol/methylene chloride) to provide3-[3-(dimethylamino)prop-2-enoyl]-5-methyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.365 g, 87%) as an orange solid.

¹H NMR (300 MHz, CDCl₃) δ ppm 2.18 (s, 3H), 2.92 (s, 3H), 3.14 (s, 3H),5.69-5.82 (m, 1H), 7.63-7.65 (m, 2H), 7.83-7.87 (m, 3H), 8.20 (s, 1H);APCI MS m/z 352 [M+H]⁺.

Reference Example 793-[3-(Dimethylamino)but-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A slurry of 3-acetyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.369 g, 1.30 mmol) in N,N-dimethylacetamide dimethylacetal (3.5 mL,18.3 mmol) was heated under microwave conditions at 120° C. for 5 min.After this time, the reaction was cooled to room temperature andconcentrated onto silica gel. The crude product was purified by columnchromatography (silica gel, dichloromethane to 90:10dichloromethane/methanol) to give3-[3-(dimethylamino)but-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.314 g, 68%) as a yellow foam.

¹H NMR (500 MHz, CDCl₃) δ ppm 2.71 (s, 3H), 3.07 (br s, 6H), 5.52 (s,1H), 6.71 (d, J=8.0 Hz, 1H), 7.59-7.69 (m, 2H), 7.76-7.85 (m, 1H), 7.87(s, 1H), 8.21 (d, J=7.9 Hz, 1H); APCI MS m/z 352 [M+H]⁺.

Reference Example 80 Methyl2-[(2-fluorophenyl)hydrazono]-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (1.66 g, 24 mmol) in H₂O (5 mL) was added dropwiseat 0° C. to a mixture of 2-fluoroaniline (1.93 mL, 20 mmol) and 6 M HClaqueous solution (20 mL, 120 mmol). After stirring for 15 min, theresulting aqueous solution was added to a suspension of methyl4-methoxyacetoacetate (2.59 mL, 20 mmol) and NaOAc (9.84 g, 120 mmol) inMeOH (40 mL) pre-cooled at 0° C. The reaction mixture was poured intowater and extracted with AcOEt. The extract was washed with saturatedNaHCO₃ aqueous solution and brine, dried over MgSO₄, and concentratedunder reduced pressure. The residue was recrystallized from hexane/AcOEtto give the title compound (5.03 g, 94% yield) as pale yellow crystals:mp 121-126° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.51 (3H, s), 3.94 (3H,s), 4.68 (2H, s), 7.08-7.25 (3H, m), 7.63 (1H, dt, J=1.5, 7.9 Hz), 13.06(1H, br s). Anal. Calcd for C₁₂H₁₃FN₂O₄: C, 53.73; H, 4.88; N, 10.44.Found: C, 53.69; H, 4.96; N, 10.47.

Reference Example 81 Methyl1-(2-fluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-[(2-fluorophenyl)hydrazono]-4-methoxy-3-oxobutanoate (5.02 g, 18.7mmol) in N,N-dimethylformamide dimethyl acetal (35 mL) was refluxed for1 h. After cooling to room temperature, the precipitate was collected byfiltration and washed with hexane/AcOEt (2/1) to give the title compound(4.70 g, 90% yield) as off-white crystals: mp 155-157° C.; ¹H NMR (300MHz, CDCl₃): δ ppm 3.91 (3H, s), 3.97 (3H, s), 7.29-7.36 (2H, m),7.44-7.51 (1H, m), 7.65 (1H, dt, J=1.9, 7.9 Hz), 7.77 (1H, d, J=2.3 Hz).Anal. Calcd for C₁₃H₁₁FN₂O₄: C, 56.12; H, 3.98; N, 10.07. Found: C,56.17; H, 3.97; N, 10.25.

Reference Example 82 1-(2-Fluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (4.74 g, 48.6mmol) and iPr₂NEt (8.47 mL, 48.6 mmol) in CH₂Cl₂ (50 mL) was added AlMe₃(1.8 M solution in toluene, 27 mL, 48.6 mmol) dropwise at 0° C. under Aratmosphere. After stirring for 1 h, a solution of methyl1-(2-fluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(4.51 g, 16.2 mmol) in CH₂Cl₂ (50 mL) was added dropwise, and themixture was stirred for 1 h at 0° C. The reaction mixture was pouredinto ice-water, acidified with 1 M HCl aqueous solution, saturated withNaCl, and extracted with AcOEt five times. The combined extracts weredried over MgSO₄, and concentrated under reduced pressure. The residuewas recrystallized from AcOEt to give the title compound (3.23 g, 65%yield) as colorless crystals: mp 152-154° C.; ¹H NMR (300 MHz, CDCl₃): δppm 3.39 (3H, s), 3.71 (3H, s), 3.91 (3H, s), 7.25-7.33 (2H, m),7.41-7.48 (1H, m), 7.65 (1H, dt, J=1.9, 7.9 Hz), 7.81 (1H, d, J=2.3 Hz).Anal. Calcd for C₁₄H₁₄FN₃O₄: C, 54.72; H, 4.59; N, 13.67. Found: C,54.85; H, 4.54; N, 13.86.

Reference Example 833-Acetyl-1-(2-fluorophenyl)-5-methoxypyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 30 mL, 30 mmol) was added dropwise at −78°C. to a solution of1-(2-fluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(3.20 g, 10.4 mmol) in THF (30 mL). After stirring for 1 h, the reactionmixture was quenched with 1 M HCl aqueous solution, saturated with NaCl,and extracted with AcOEt five times. The combined extracts were driedover MgSO₄, and concentrated under reduced pressure. The residue wasrecrystallized from AcOEt to give the title compound (2.32 g, 85% yield)as pale yellow crystals: mp 154-156° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm2.69 (3H, s), 3.91 (3H, s), 7.27-7.38 (2H, m), 7.45-7.53 (1H, m), 7.65(1H, dt, J=1.5, 7.9 Hz), 7.77 (1H, d, J=2.3 Hz). Anal. Calcd forC₁₃H₁₁FN₂O₃: C, 59.54; H, 4.23; N, 10.68. Found: C, 59.62; H, 4.22; N,10.79.

Reference Example 84 Methyl2-{[2-(difluoromethoxy)phenyl]hydrazono}-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (2.378 g, 34.5 mmol) in H₂O (10 mL) was addeddropwise at 0° C. to a solution of 2-(difluoromethoxy)aniline (3.59 mL,28.7 mmol) in 6 M HCl aqueous solution (28.7 mL, 172 mmol). Afterstirring for 15 min, the resulting aqueous solution was added to asuspension of methyl 4-methoxyacetoacetate (3.72 mL, 28.7 mmol) andNaOAc (14.14 g, 172 mmol) in MeOH (50 mL) pre-cooled at 0° C. Theprecipitate was collected by filtration, washed with water, anddissolved in AcOEt. The organic solution was washed with water,saturated NaHCO₃ aqueous solution and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was washed withhexane/AcOEt (3/1) to give the title compound (8.70 g, 96% yield) asyellow crystals: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.51 (3H, s), 3.89(3H×0.5, s), 3.94 (3H×0.5, s), 4.68 (1H×0.5, s), 4.70 (1H×0.5, s), 6.63(1H×0.5, t, J=72.7 Hz), 6.66 (1H×0.5, t, J=72.3 Hz), 7.10-7.34 (4H, m),7.67 (1H×0.5, dd, J=8.3, 1.5 Hz), 7.90 (1H×0.5, dd, J=8.3, 1.5 Hz),13.14 (1H×0.5, s), 14.96 (1H×0.5, br s).

Reference Example 85 Methyl1-[2-(difluoromethoxy)phenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-{[2-(difluoromethoxy)phenyl]hydrazono}-4-methoxy-3-oxobutanoate (8.70g, 27.5 mmol) in N,N-dimethylformamide dimethyl acetal (60 mL) wasrefluxed for 3 h and stirred at room temperature for 3 days. Theprecipitate was collected by filtration and washed with hexane/AcOEt(3/1) to give the title compound (7.92 g, 88% yield) as yellow crystals:¹H NMR (300 MHz, CDCl₃): δ ppm 3.89 (3H, s), 3.96 (3H, s), 6.55 (1H, d,J=72.7 Hz), 7.35-7.45 (2H, m), 7.49-7.56 (1H, m), 7.61 (1H, dd, J=7.9,1.5 Hz), 7.73 (1H, s).

Reference Example 861-[2-(Difluoromethoxy)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (5.27 g, 54.0mmol) and iPr₂NEt (9.40 mL, 54.0 mmol) in CH₂Cl₂ (60 mL) was added AlMe₃(1.8 M solution in toluene, 30.0 mL, 54.0 mmol) dropwise at 0° C. Afterstirring at 0° C. for 1 h, a solution of methyl1-[2-(difluoromethoxy)phenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(5.87 g, 17.99 mmol) in CH₂Cl₂ (60 mL) was added dropwise, and themixture was stirred at 0° C. for 1 h. The reaction mixture was pouredinto ice-water and extracted with AcOEt. The extract was washed withbrine, dried over MgSO₄, and concentrated under reduced pressure. Theresidue was washed with hexane/AcOEt (3/1) to give the title compound(4.79 g, 75% yield) as pale yellow crystals: ¹H NMR (300 MHz, CDCl₃): δppm 3.38 (3H, s), 3.68 (3H, s), 3.89 (3H, s), 6.52 (1H, t, J=72.6 Hz),7.37 (2H, m), 7.46-7.53 (1H, m), 7.62 (1H, dd, J=7.8, 1.5 Hz), 7.76 (1H,s).

Reference Example 873-Acetyl-1-[2-(difluoromethoxy)phenyl]-5-methoxypyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 40.4 ml, 40.4 mmol) was added dropwise at−78° C. to a solution of1-[2-(difluoromethoxy)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(4.79 g, 13.48 mmol) in THF (500 mL). After stirring for 1 h, thereaction mixture was quenched with 1 M HCl aqueous solution and warm toroom temperature. The reaction mixture was concentrated under reducedpressure and extracted with AcOEt. The extract was washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by silica gel column chromatography eluting withhexane/AcOEt (1/1-0/1) and recrystallized from diisopropyl ether/AcOEtto give the title compound (3.33 g, 80% yield) as colorless crystals: ¹HNMR (300 MHz, CDCl₃): δ ppm 2.68 (3H, s), 3.89 (3H, s), 6.55 (1H, t,J=72.7 Hz), 7.36-7.45 (2H, m), 7.50-7.57 (1H, m), 7.61 (1H, dd, J=7.8,1.7 Hz), 7.72 (1H, s).

Reference Example 881-[2-(Difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]-5-methoxypyridazin-4(1H)-one

A mixture of3-acetyl-1-[2-(difluoromethoxy)phenyl]-5-methoxypyridazin-4(1H)-one(3.70 g, 11.93 mmol) and N,N-dimethylformamide dimethyl acetal (50 mL)was refluxed for 5 h and stirred overnight at room temperature. Theprecipitate was collected by filtration and washed with AcOEt to givethe title compound (4.07 g, 93% yield) as yellow crystals: ¹H NMR (300MHz, CDCl₃): δ ppm 2.90 (3H, s), 3.12 (3H, br s), 3.87 (3H, s), 5.87(1H, br s), 6.31-6.82 (2H, m), 7.30-7.41 (2H, m), 7.43-7.50 (1H, m),7.63 (1H, dd, J=7.8, 1.8 Hz), 7.74 (1H, s).

Reference Example 89 Methyl4-methoxy-3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}butanoate

A solution of NaNO₂ (4.14 g, 60 mmol) in H₂O (15 mL) was added dropwiseat 0° C. to a mixture of 3-(trifluoromethyl)aniline (6.24 mL, 50 mmol)and 6 M HCl aqueous solution (50 mL, 300 mmol). After stirring for 15min, the resulting aqueous solution was added to a suspension of methyl4-methoxyacetoacetate (7.31 mL, 50 mmol) and NaOAc (24.6 g, 300 mmol) inEtOH (80 mL) pre-cooled at 0° C. The precipitate was collected byfiltration, washed with water, and dissolved in AcOEt. The organicsolution was washed with water and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was crystallized fromhexane/AcOEt to give the title compound (14.0 g, 88% yield) as paleyellow crystals: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.51 (3H×0.36, s), 3.52(3H×0.64, s), 3.90 (3H×0.36, s), 3.94 (3H×0.64, s), 4.68 (2H×0.64, s),4.70 (2H×0.36, s), 7.41-7.59 (3H+1H×0.64, m), 7.71 (1H×0.36, s), 13.00(1H×0.64, s), 14.87 (1H×0.36, s).

Reference Example 90 Methyl5-methoxy-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate

A solution of methyl4-methoxy-3-oxo-2-{[3-(trifluoromethyl)phenyl]hydrazono}butanoate (14.0g, 44 mmol) in N,N-dimethylformamide dimethyl acetal (100 mL) wasrefluxed for 4 h. After cooling to room temperature, the precipitate wascollected by filtration and washed with hexane/AcOEt (3/1) to give thetitle compound (12.9 g, 89% yield) as off-white crystals: mp 169-170°C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.98 (3H, s), 3.99 (3H, s), 7.66-7.74(2H, m), 7.83-7.89 (2H, m), 7.95 (1H, s). Anal. Calcd for C₁₄H₁₁F₃N₂O₄:C, 51.23; H, 3.38; N, 8.53. Found: C, 51.15; H, 3.47; N, 8.60.

Reference Example 91N,5-Dimethoxy-N-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (2.63 g, 27mmol) and iPr₂NEt (4.70 mL, 27 mmol) in CH₂Cl₂ (30 mL) was added AlMe₃(1.8 M solution in toluene, 15 mL, 27 mmol) dropwise at 0° C. under Aratmosphere. After stirring for 1 h, a solution of methyl5-methoxy-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(2.95 g, 9 mmol) in CH₂Cl₂ (30 mL) was added dropwise, and the mixturewas stirred for 1 h at 0° C. The reaction mixture was poured intoice-water and extracted with AcOEt. The extract was washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by basic silica gel column chromatography eluting withAcOEt and recrystallized from hexane/AcOEt to give the title compound(2.15 g, 67% yield) as off-white crystals: mp 170-171° C.; ¹H NMR (300MHz, CDCl₃): δ ppm 3.41 (3H, s), 3.71 (3H, s), 3.98 (3H, s), 7.63-7.71(2H, m), 7.80-7.86 (1H, m), 7.88 (1H, s), 7.98 (1H, s). Anal. Calcd forC₁₅H₁₄F₃N₃O₄: C, 50.42; H, 3.95; N, 11.76. Found: C, 50.48; H, 4.07; N,11.66.

Reference Example 923-Acetyl-5-methoxy-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

MeMgBr (3 M solution in diethyl ether, 4 mL, 12 mmol) was added dropwiseat −78° C. to a solution ofN,5-dimethoxy-N-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(2.09 g, 5.85 mmol) in THF (50 mL). After stirring for 1 h, the reactionmixture was quenched with saturated NH₄Cl aqueous solution and extractedwith AcOEt three times. The combined extracts were washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by silica gel column chromatography eluting with AcOEt/MeOH(1/0-10/1) and recrystallized from hexane/AcOEt to give the titlecompound (1.44 g, 79% yield) as off-white crystals: mp 155-156° C.; ¹HNMR (300 MHz, CDCl₃): δ ppm 2.71 (3H, s), 3.98 (3H, s), 7.68-7.76 (2H,m), 7.83-7.88 (2H, m), 7.94 (1H, s). Anal. Calcd for C₁₄H₁₁F₃N₂O₃: C,53.85; H, 3.55; N, 8.97. Found: C, 53.79; H, 3.59; N, 9.02.

Reference Example 933-[3-(Dimethylamino)prop-2-enoyl]-5-methoxy-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-acetyl-5-methoxy-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(1.39 g, 4.45 mmol) in N,N-dimethylformamide dimethyl acetal (15 mL) wasrefluxed for 3 h. After cooling to room temperature, the reactionmixture was concentrated under reduced pressure, and the residue wasdissolved in AcOEt. The organic solution was washed with half-saturatedbrine, and the aqueous solution was extracted with AcOEt four times. Thecombined organic layers were dried over MgSO₄, and concentrated underreduced pressure. The residue was recrystallized from AcOEt to give thetitle compound (1.46 g, 89% yield) as orange crystals: mp 176-178° C.;¹H NMR (300 MHz, CDCl₃): δ ppm 2.91 (3H, s), 3.14 (3H, s), 3.96 (3H, s),5.80 (1H, d, J=13.2 Hz), 7.61-7.68 (2H, m), 7.80 (1H, br s), 7.84-7.90(2H, m), 7.96 (1H, s). Anal. Calcd for C₁₇H₁₆F₃N₃O₃: C, 55.59; H, 4.39;N, 11.44. Found: C, 55.32; H, 4.51; N, 11.30.

Reference Example 94 Methyl2-[(2-fluoro-4-iodophenyl)hydrazono]-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (1.66 g, 24 mmol) in H₂O (5 mL) was added dropwiseat 0° C. to a mixture of 2-fluoro-4-iodoaniline (4.74 g, 20 mmol) and 6M HCl aqueous solution (20 mL, 120 mmol). After stirring for 15 min, theresulting aqueous solution was added to a suspension of methyl4-methoxyacetoacetate (2.59 mL, 20 mmol) and NaOAc (9.84 g, 120 mmol) inMeOH (40 mL) pre-cooled at 0° C. The reaction mixture was poured intowater and extracted with AcOEt. The extract was washed with saturatedNaHCO₃ aqueous solution and brine, dried over MgSO₄, and concentratedunder reduced pressure. The residue was recrystallized from hexane/AcOEtto give the title compound (6.29 g, 80% yield) as yellow crystals: mp141-146° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.50 (3H, s), 3.93 (3H, s),4.64 (2H, s), 7.35 (1H, t, J=8.5 Hz), 7.49-7.55 (2H, m), 12.97 (1H, brs). Anal. Calcd for C₁₂H₁₂FIN₂O₄: C, 36.57; H, 3.07; N, 7.11. Found: C,36.74; H, 3.10; N, 7.32.

Reference Example 95 Methyl1-(2-fluoro-4-iodophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-[(2-fluoro-4-iodophenyl)hydrazono]-4-methoxy-3-oxobutanoate (6.27 g,15.9 mmol) in N,N-dimethylformamide dimethyl acetal (60 mL) was refluxedfor 3 h. After cooling to room temperature, the reaction mixture waspoured into water and extracted with AcOEt. The extract was washed withwater and brine, dried over MgSO₄, and concentrated under reducedpressure. The residue was purified by silica gel column chromatographyeluting with AcOEt and recrystallized from MeOH to give the titlecompound (3.77 g, 59% yield) as off-white crystals: mp 160-162° C.; ¹HNMR (300 MHz, CDCl₃): δ ppm 3.90 (3H, s), 3.97 (3H, s), 7.36-7.41 (1H,m), 7.64-7.70 (2H, m), 7.73 (1H, d, J=2.6 Hz). Anal. Calcd forC₁₃H₁₀FIN₂O₄: C, 38.64; H, 2.49; N, 6.93. Found: C, 38.68; H, 2.59; N,6.98.

Reference Example 961-(2-Fluoro-4-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (8.78 g, 90mmol) and iPr₂NEt (15.7 mL, 90 mmol) in CH₂Cl₂ (100 mL) was added AlMe₃(1.8 M solution in toluene, 50 mL, 90 mmol) slowly at 0° C. under Aratmosphere. After stirring for 1 h, a solution of methyl1-(2-fluoro-4-iodophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(12.1 g, 30 mmol) in CH₂Cl₂ (100 mL) was added slowly, and the mixturewas stirred for 1 h at 0° C. The reaction mixture was poured intoice-water and the organic layer was separated. The aqueous layer wasextracted with AcOEt. The combined extracts were washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by basic silica gel column chromatography eluting withAcOEt to give the title compound (9.96 g, 77% yield) as a whiteamorphous solid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.39 (3H, s), 3.70 (3H,s), 3.90 (3H, s), 7.39 (1H, t, J=8.1 Hz), 7.63-7.67 (2H, m), 7.77 (1H,d, J=2.3 Hz).

Reference Example 973-Acetyl-1-(2-fluoro-4-iodophenyl)-5-methoxypyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 70 mL, 70 mmol) was added dropwise at −78°C. to a solution of1-(2-fluoro-4-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(9.96 g, 23 mmol) in THF (250 mL). After stirring for 1 h, the reactionmixture was quenched with 1 M HCl aqueous solution and extracted withAcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with AcOEt and recrystallized fromMeOH to give the title compound (2.05 g, 23% yield) as pale yellowcrystals: mp 196-198° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 2.67 (3H, s),3.90 (3H, s), 7.36-7.41 (1H, m), 7.66-7.71 (2H, m), 7.73 (1H, d, J=2.6Hz). Anal. Calcd for C₁₃H₁₀FIN₂O₃: C, 40.23; H, 2.60; N, 7.22. Found:40.25; H, 2.87; N, 7.28.

Reference Example 98 Methyl5-(methoxymethyl)-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate

A solution of NaNO₂ (2.48 g, 36 mmol) in H₂O (10 mL) was added dropwiseat 0° C. to a mixture of 3-(trifluoromethyl)aniline (3.75 mL, 30 mmol)and 6 M HCl aqueous solution (30 mL, 180 mmol). After stirring for 15min, the resulting aqueous solution was added to a suspension of methyl5-methoxy-3-oxovalerate (4.37 mL, 30 mmol) and NaOAc (14.8 g, 180 mmol)in EtOH (50 mL) pre-cooled at 0° C. After stirring for 5 min, thereaction mixture was poured into water and extracted with AcOEt. Theextract was washed with saturated NaHCO₃ aqueous solution and brine,dried over MgSO₄, and concentrated under reduced pressure.

A solution of the residue in N,N-dimethylformamide dimethyl acetal (50mL) was refluxed for 4 h. After cooling to room temperature, theprecipitate was collected by filtration and recrystallized from AcOEt togive the title compound (7.13 g, 69% yield) as a yellow solid: mp138-140° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.53 (3H, s), 4.00 (3H, s),4.49 (2H, d, J=1.5 Hz), 7.65-7.73 (2H, m), 7.82-7.85 (1H, m), 7.89 (1H,s), 8.38 (1H, t, J=1.5 Hz). Anal. Calcd for C₁₅H₁₃F₃N₂O₄: C, 52.64; H,3.83; N, 8.18. Found: C, 52.50; H, 3.89; N, 8.17.

Reference Example 99N-Methoxy-5-(methoxymethyl)-N-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (2.63 g, 27mmol) and iPr₂NEt (4.70 mL, 27 mmol) in CH₂Cl₂ (30 mL) was added AlMe₃(1.8 M solution in toluene, 15 mL, 27 mmol) dropwise at 0° C. under Aratmosphere. After stirring for 1 h, a solution of methyl5-(methoxymethyl)-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(3.08 g, 9 mmol) in CH₂Cl₂ (30 mL) was added dropwise, and the mixturewas stirred for 1 h at 0° C. The reaction mixture was poured intoice-water and extracted with AcOEt. The extract was washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by silica gel column chromatography eluting with AcOEt andrecrystallized from hexane/AcOEt to give the title compound (1.99 g, 60%yield) as an off-white solid: mp 157-159° C.; ¹H NMR (300 MHz, CDCl₃): δppm 3.41 (3H, s), 3.53 (3H, s), 3.67 (3H, s), 4.50 (2H, d, J=1.1 Hz),7.62-7.71 (2H, m), 7.79-7.85 (1H, m), 7.90 (1H, s), 8.39 (1H, t, J=1.1Hz). Anal. Calcd for C₁₆H₁₆F₃N₃O₄: C, 51.75; H, 4.34; N, 11.32. Found:C, 51.77; H, 4.25; N, 11.24.

Reference Example 1003-Acetyl-5-(methoxymethyl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 16 mL, 16 mmol) was added dropwise at −78°C. to a solution ofN-methoxy-5-(methoxymethyl)-N-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(1.95 g, 5.25 mmol) in THF (50 mL). After stirring for 1 h, the reactionmixture was quenched with saturated NH₄Cl aqueous solution and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with AcOEt and recrystallized fromhexane/AcOEt to give the title compound (1.42 g, 83% yield) as a paleyellow solid: mp 141-143° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 2.68 (3H,s), 3.54 (3H, s), 4.50 (2H, d, J=1.5 Hz), 7.66-7.74 (2H, m), 7.81-7.87(1H, m), 7.89 (1H, s), 8.38 (1H, t, J=1.5 Hz). Anal. Calcd forC₁₅H₁₃F₃N₂O₃: C, 55.22; H, 4.02; N, 8.59. Found: C, 55.26; H, 3.95; N,8.58.

Reference Example 1013-Acetyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of 3-{[3-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione(5.00 g, 18.4 mmol) and N,N-dimethylformamide dimethyl acetal (2.44 mL,18.4 mmol) in DMF (100 mL) was heated to 80° C. for 4 h. The mixture wasdiluted with 1 M HCl aqueous solution, extracted with EtOAc, washed withbrine, dried over Na₂SO₄, filtered, concentrated in vacuo, purified bycolumn chromatography on silica gel (hexane/EtOAc=50/50 to 0/100 andEtOAc/MeOH=100/0 to 80/20) and triturated with EtOAc/hexane to yield thetitle compound (3.38 g, 65% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 2.55 (3H, s), 6.75 (1H, d, J=8.0 Hz),7.78-7.88 (2H, m), 8.06-8.16 (2H, m), 8.96 (1H, d, J=8.2 Hz).

Reference Example 1023-Acetyl-5-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-acetyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (1.00 g, 3.54mmol) in AcOH (3.5 mL) was added Br₂ (0.181 mL, 3.54 mmol) at roomtemperature. The mixture was stirred at room temperature for 2 h. Themixture was diluted with water and NaHCO₃ aqueous solution, extractedwith EtOAc, dried over MgSO₄, filtered, concentrated in vacuo andpurified by column chromatography on silica gel (hexane/EtOAc=50/50 to0/100) to yield the title compound (332 mg, 26% yield) as a pale yellowsolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 2.57 (3H, s), 7.79-7.91 (2H, m),8.09-8.17 (1H, m), 8.22 (1H, s), 9.58 (1H, s).

Reference Example 103 Methyl4-methoxy-6-oxo-1-[3-(trifluoromethyl)phenyl]-1,6-dihydropyridazine-3-carboxylate

A solution of NaNO₂ (2.07 g, 30 mmol) in H₂O (10 mL) was added dropwiseat 0° C. to a mixture of 3-(trifluoromethyl)aniline (3.12 mL, 25 mmol)and 6 M HCl aqueous solution (25 mL, 150 mmol). After stirring for 15min, the resulting aqueous solution was added to a suspension ofdimethyl 1,3-acetonedicarboxylate (3.61 mL, 25 mmol) and NaOAc (12.3 g,150 mmol) in EtOH (40 mL) pre-cooled at 0° C. After stirring for 10 min,the reaction mixture was poured into water and extracted with AcOEt. Theextract was washed with saturated NaHCO₃ aqueous solution and brine,dried over MgSO₄, and concentrated under reduced pressure.

A solution of the residue and NaOMe (2.70 g, 50 mmol) in MeOH (50 mL)was stirred for 30 min at room temperature. The reaction mixture waspoured into 1 M HCl aqueous solution and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure.

A suspension of the residue, MeI (3.11 mL, 50 mmol), and K₂CO₃ (10.4 g,75 mmol) in DMF (50 mL) was stirred for 1 h at room temperature. Thereaction mixture was poured into water and extracted with AcOEt. Theextract was washed with water and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/AcOEt (1/1) andrecrystallized from hexane/AcOEt to give the title compound (1.83 g, 22%yield) as a pale yellow solid: mp 124-125° C.; ¹H NMR (300 MHz, CDCl₃):δ ppm 3.94 (3H, s), 3.95 (3H, s), 6.32 (1H, s), 7.57-7.62 (1H, m),7.65-7.68 (1H, m), 7.80-7.84 (1H, m), 7.88 (1H, s). Anal. Calcd forC₁₄H₁₁F₃N₂O₄: C, 51.23; H, 3.38; N, 8.53. Found: C, 51.29; H, 3.40; N,8.52.

Reference Example 104N,4-Dimethoxy-N-methyl-6-oxo-1-[3-(trifluoromethyl)phenyl]-1,6-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (1.58 g, 16.2mmol) and iPr₂NEt (2.82 mL, 16.2 mmol) in CH₂Cl₂ (13 mL) was added AlMe₃(1.8 M solution in toluene, 9.0 mL, 16.2 mmol) dropwise at 0° C. underAr atmosphere. After stirring for 1 h, a solution of methyl4-methoxy-6-oxo-1-[3-(trifluoromethyl)phenyl]-1,6-dihydropyridazine-3-carboxylate(1.77 g, 5.4 mmol) in CH₂Cl₂ (15 mL) was added dropwise, and the mixturewas stirred for 1 h at 0° C. The reaction mixture was poured intoice-water and extracted with AcOEt. The extract was washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by silica gel column chromatography eluting with AcOEt andcrystallized from hexane/AcOEt to give the title compound (1.48 g, 83%yield) as a white solid: mp 127-129° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.37 (3H, s), 3.64 (3H, s), 3.91 (3H, s), 6.30 (1H, s), 7.55-7.60 (1H,m), 7.62-7.65 (1H, m), 7.82-7.86 (1H, m), 7.88 (1H, s). Anal. Calcd forC₁₅H₁₄F₃N₃O₄: C, 50.42; H, 3.95; N, 11.76. Found: C, 50.47; H, 3.99; N,11.83.

Reference Example 1056-Acetyl-5-methoxy-2-[3-(trifluoromethyl)phenyl]pyridazin-3 (2H)-one

MeMgBr (1 M solution in THF, 4 mL, 12 mmol) was added dropwise at −78°C. to a solution ofN,4-dimethoxy-N-methyl-6-oxo-1-[3-(trifluoromethyl)phenyl]-1,6-dihydropyridazine-3-carboxamide(1.43 g, 4 mmol) in THF (15 mL). After stirring for 1 h, the reactionmixture was quenched with saturated NH₄Cl aqueous solution and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with hexane/AcOEt (1/1) andrecrystallized from hexane/AcOEt to give the title compound (566 mg, 45%yield) as a white solid: mp 136-138° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm2.57 (3H, s), 3.93 (3H, s), 6.31 (1H, s), 7.63 (1H, t, J=7.9 Hz), 7.69(1H, d, J=7.9 Hz), 7.84-7.88 (1H, m), 7.91 (1H, s). Anal. Calcd forC₁₄H₁₁F₃N₂O₃: C, 53.85; H, 3.55; N, 8.97. Found: C, 53.96; H, 3.57; N,8.96.

Reference Example 1065-Methoxy-6-(1-phenyl-1H-pyrazol-5-yl)-2-[3-(trifluoromethyl)phenyl]pyridazin-3(2H)-one

A solution of6-acetyl-5-methoxy-2-[3-(trifluoromethyl)phenyl]pyridazin-3(2H)-one (540mg, 1.73 mmol) in N,N-dimethylformamide dimethyl acetal (5 mL) wasrefluxed for 3 h. After cooling to room temperature, the reactionmixture was concentrated under reduced pressure. The residue was dilutedwith AcOEt, washed with water and brine, dried over MgSO₄, andconcentrated under reduced pressure.

A solution of the residue and phenylhydrazine (0.551 mL, 5.19 mmol) inMeOH (5 mL) was refluxed for 2 h. After cooling to room temperature, thereaction mixture was poured into 1 M HCl aqueous solution and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with hexane/AcOEt (1/1) andrecrystallized from hexane/AcOEt to give the title compound (323 mg, 45%yield) as a white solid: mp 165-167° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.73 (3H, s), 6.27 (1H, s), 6.78 (1H, d, J=1.9 Hz), 7.31-7.50 (8H, m),7.52-7.58 (1H, m), 7.77 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 413 [M+H]⁺.Anal. Calcd for C₂₁H₁₅F₃N₄O₂: C, 61.17; H, 3.67; N, 13.59. Found: C,61.12; H, 3.72; N, 13.54.

Reference Example 1074-Oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylicacid

To a suspension of methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(10.0 g, 33.5 mmol) in MeOH (150 mL) was added 1 M NaOH aqueous solution(50 mL) at 0° C. The mixture was stirred at room temperature for 30 min.To the suspension was added 1 M HCl aqueous solution (50 mL) at 0° C.The mixture was concentrated in vacuo. The precipitates were collectedby filtration, washed with water and dried in vacuo at 50° C. to yieldthe title compound (9.25 g, 97% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 7.02 (1H, d, J=7.7 Hz), 7.81-7.96 (2H, m),8.06-8.21 (2H, m), 9.16 (1H, d, J=7.7 Hz).

Reference Example 108N-Methoxy-N-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide

A mixture of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylicacid (2.00 g, 7.04 mmol) and CDI (1.26 g, 7.74 mmol) in THF (20 mL) washeated to 40° C. for 2 h. To the solution were addedN-methoxymethanamine hydrochloride (1.03 g, 10.6 mmol) and i-Pr₂NEt(1.84 mL, 10.6 mmol) at room temperature. The solution was stirred atroom temperature for 20 h. The mixture was diluted with water, extractedwith EtOAc, washed with brine, dried over Na₂SO₄, filtered, concentratedin vacuo and purified by column chromatography on silica gel(hexane/EtOAc=50/50 to 0/100 and EtOAc/MeOH=100/0 to 80/20) to yield thecrude title compound (2.40 g) as a pale yellow solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 3.28 (3H, s), 3.61 (3H, s), 6.67 (1H, d, J=7.9 Hz),7.77-7.90 (2H, m), 8.00-8.14 (2H, m), 8.99 (1H, d, J=7.9 Hz).

Reference Example 1093-Propanoyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution ofN-methoxy-N-methyl-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(1.20 g, 3.52 mmol) in THF (20 mL) was added EtMgBr (1.0 M in THF, 7.04mL, 7.04 mmol) at −78° C. under N₂. The mixture was stirred at −78° C.for 1 h. The reaction was quenched with saturated NH₄Cl aqueous solutionat −78° C. The mixture was warmed to room temperature, extracted withEtOAc, dried over Na₂SO₄, filtered, concentrated in vacuo and purifiedby column chromatography on silica gel (hexane/EtOAc=50/50 to 0/100) toyield the title compound (767 mg, 74% yield) as a pale yellow solid: ¹HNMR (DMSO-d₆, 300 MHz): δ ppm 1.06 (3H, t, J=7.2 Hz), 2.99 (2H, q, J=7.2Hz), 6.73 (1H, d, J=8.3 Hz), 7.79-7.88 (2H, m), 8.06-8.17 (2H, m), 8.97(1H, d, J=8.3 Hz).

Reference Example 110 4-Bromo-3-phenyl-1H-pyrazole

A solution of 3-phenyl-1H-pyrazole (4.08 g, 28.3 mmol) and NBS (5.04 g,28.3 mmol) in DMF (40 mL) was stirred for 1 h at room temperature. Thereaction mixture was poured into water and extracted with AcOEt. Theextract was washed with water and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was recrystallized fromhexane/AcOEt to give the title compound (5.84 g, 93% yield) as a whitesolid: mp 114-116° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 7.39-7.50 (3H, m),7.64 (1H, s), 7.77 (2H, d, J=6.8 Hz), 10.73 (1H, brs).

Reference Example 111 4-Bromo-3-phenyl-1-trityl-1H-pyrazole

A suspension of 4-bromo-3-phenyl-1H-pyrazole (6.13 g, 27.5 mmol), tritylchloride (15.3 g, 55.0 mmol), and K₂CO₃ (11.4 g, 82.5 mmol) in DMF (100mL) was stirred for 60 h at 90° C. After cooling to room temperature,the reaction mixture was poured into water and extracted with AcOEt. Theextract was washed with water and brine, dried over MgSO₄, concentratedunder reduced pressure. The residue was recrystallized from hexane/THFto give the title compound (8.00 g, 63% yield) as a white solid: mp181-183° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 7.16-7.22 (6H, m), 7.28-7.41(13H, m), 7.87-7.91 (2H, m). Anal. Calcd for C₂₈H₂₁BrN₂: C, 72.26; H,4.55; N, 6.02. Found: C, 72.43; H, 4.66; N, 5.91.

Reference Example 1123-Amino-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylicacid (5.00 g, 17.6 mmol), DPPA (5.67 mL, 26.4 mmol) and Et₃N (3.65 mL,26.4 mmol) in toluene (35 mL) was heated to 100° C. for 2 h. To themixture was added 8 M NaOH aqueous solution (22 mL) at 0° C. The mixturewas stirred at room temperature for 2 h, diluted with brine, extractedwith EtOAc, dried over Na₂SO₄, filtered, and concentrated in vacuo. Theresidue was washed with EtOAc/i-Pr₂O and filtered. The filtrate wasconcentrated in vacuo, purified by column chromatography on basic silicagel (hexane/EtOAc=50/50 to 0/100) and washed with EtOAc/hexane to yieldthe title compound (2.50 g, 56% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 6.17 (1H, d, J=7.5 Hz), 6.52 (2H, brs),7.67-7.81 (2H, m), 8.04 (1H, d, J=7.5 Hz), 8.10 (1H, s), 8.75 (1H, d,J=7.5 Hz).

Reference Example 1133-Bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To DMF (18 mL) were added isoamyl nitrite (2.44 mL, 18.3 mmol) and CuBr₂(1.89 g, 8.46 mmol) at 0° C. To the mixture was dropwise added asolution of 3-amino-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(1.80 g, 7.05 mmol) in DMF (7.2 mL) at 0° C. The mixture was stirred at0° C. for 1 h and at 60° C. for 3 h. The mixture was diluted with brine,extracted with EtOAc, washed with brine, dried over MgSO₄, filtered,concentrated in vacuo, purified by column chromatography on silica gel(hexane/EtOAc=50/50 to 0/100) and triturated with hexane to yield thetitle compound (1.85 g, 82% yield) as a white solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 6.64 (1H, d, J=7.7 Hz), 7.78-7.87 (2H, m), 8.01-8.07(1H, m), 8.08 (1H, s), 9.00 (1H, d, J=7.7 Hz).

Reference Example 1141-[3-(Trifluoromethyl)phenyl]-3-[(trimethylsilyl)ethynyl]pyridazin-4(1H)-one

A mixture of 3-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(500 mg, 1.57 mmol), (trimethylsilyl)acetylene (0.222 mL, 1.57 mmol),Et₃N (0.329 mL, 2.36 mmol), CuI (4.5 mg, 0.0236 mmol), Pd(PPh₃)₂Cl₂(55.1 mg, 0.0785 mmol) and PPh₃ (10.3 mg, 0.0393 mmol) in THF (7.5 mL)was heated to 40° C. for 8 h under Ar. To the suspension was added(trimethylsilyl)acetylene (0.111 mL, 0.785 mmol). The suspension washeated to 40° C. for 14 h under Ar. To the suspension was added(trimethylsilyl)acetylene (0.0888 mL, 0.628 mmol). The suspension washeated to 40° C. for 96 h under Ar. The mixture was diluted with brine,extracted with EtOAc, dried over MgSO₄, filtered, concentrated in vacuoand purified by column chromatography on silica gel (hexane/EtOAc=50/50to 0/100) to yield the title compound (148 mg, 28% yield) as a brownsolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 0.26 (9H, s), 6.64 (1H, d, J=7.9Hz), 7.75-7.92 (2H, m), 8.00-8.15 (2H, m), 8.90 (1H, d, J=8.3 Hz).

Reference Example 1153-Ethynyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of1-[3-(trifluoromethyl)phenyl]-3-[(trimethylsilyl)ethynyl]pyridazin-4(1H)-one(148 mg, 0.439 mmol) in MeOH (3 mL) and 1 M NaOH aqueous solution (5 mL)was stirred at 0° C. for 5 min and at room temperature for 2 h. Themixture was neutralized with 1 M HCl aqueous solution at 0° C. Themixture was extracted with EtOAc, washed with brine, dried over Na₂SO₄,filtered, concentrated in vacuo and purified by column chromatography onsilica gel (hexane/EtOAc=50/50 to 0/100) to yield the title compound (69mg, 59% yield) as a pale red solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm4.70 (1H, s), 6.65 (1H, d, J=7.9 Hz), 7.76-7.92 (2H, m), 7.99-8.17 (2H,m), 8.93 (1H, d, J=7.9 Hz).

Reference Example 1163-(Hydroxymethyl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of methyl4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(2.00 g, 6.70 mmol) in THF (134 mL) was added DIBAL (1.5 M in toluene,13.4 mL, 20.1 mmol) at −78° C. The solution was stirred at −78° C. for 1h, gradually warmed to room temperature, stirred at room temperature for18 h, diluted with 1 M HCl aqueous solution at 0° C., extracted withEtOAc, washed with brine, dried over MgSO₄, filtered, concentrated invacuo and purified by column chromatography on silica gel(hexane/EtOAc=50/50 to 0/100 and EtOAc/MeOH=100/0 to 70/30) to yield thetitle compound (509 mg, 28% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 4.53 (2H, d, J=6.0 Hz), 5.11-5.16 (1H, m),6.48 (1H, d, J=8.0 Hz), 7.76-7.84 (2H, m), 8.08-8.16 (1H, m), 8.19 (1H,s), 8.94 (1H, d, J=8.0 Hz).

Reference Example 1174-Oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbaldehyde

To a solution of oxalyl chloride (0.175 mL, 2.07 mmol) in THF (7.5 mL)was added DMSO (0.294 mL, 4.14 mmol) at −78° C. To the suspension wasadded a solution of3-(hydroxymethyl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (509mg, 1.88 mmol) in THF (7.5 mL) at −78° C. The suspension was stirred at−78° C. for 1 h. To the mixture was added Et₃N (1.05 mL, 7.52 mmol) at−78° C. The mixture was gradually warmed to room temperature, stirred atroom temperature for 18 h, diluted with 1 M HCl aqueous solution,extracted with EtOAc, washed with saturated NaHCO₃ aqueous solution andbrine, dried over Na₂SO₄, filtered, concentrated in vacuo and purifiedby column chromatography on silica gel (hexane/EtOAc=50/50 to 0/100 andEtOAc/MeOH=100/0 to 70/30). To a solution of oxalyl chloride (0.477 mL,5.64 mmol) in THF (19 mL) was added DMSO (0.801 mL, 11.3 mmol) at −78°C. To the suspension was added a mixture of the above residue in THF(9.5 mL) at −78° C. The suspension was stirred at −78° C. for 2 h. Tothe mixture was added Et₃N (3.14 mL, 22.6 mmol) at −78° C. The mixturewas gradually warmed to room temperature, stirred at room temperaturefor 17 h, diluted with 1 M HCl aqueous solution, extracted with EtOAc,washed with saturated NaHCO₃ aqueous solution and brine, dried overNa₂SO₄, filtered, concentrated in vacuo and purified by columnchromatography on silica gel (hexane/EtOAc=50/50 to 0/100) to yield thetitle compound (257 mg, 51% yield) as a yellow solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 6.87 (1H, d, J=8.2 Hz), 7.81-7.91 (2H, m), 8.08-8.15(1H, m), 8.16 (1H, s), 8.98 (1H, d, J=8.0 Hz), 10.07 (1H, s).

Reference Example 1185-Methoxy-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylicacid

To a suspension of methyl5-methoxy-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylate(10.0 g, 30.5 mmol) in MeOH (100 mL) was added 1 M NaOH aqueous solution(61 mL) at 0° C. The mixture was stirred at room temperature for 30 min.To the solution was added 1 M HCl aqueous solution (61 mL) at 0° C. Themixture was concentrated in vacuo. The precipitates were collected byfiltration, washed with water and dried in vacuo at 60° C. to yield thetitle compound (8.78 g, 92% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.98 (3H, s), 7.82-8.01 (2H, m), 8.11-8.34(2H, m), 8.97 (1H, s), 15.00 (1H, brs).

Reference Example 1193-Amino-5-methoxy-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of5-methoxy-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxylicacid (6.00 g, 19.1 mmol), DPPA (6.16 mL, 28.6 mmol) and Et₃N (3.99 mL,28.6 mmol) in toluene (60 mL) was heated to 100° C. for 2 h. To themixture was added 8 M NaOH aqueous solution (23.8 mL) at 0° C. Themixture was stirred at room temperature for 3 h, extracted with EtOAc,dried over Na₂SO₄, filtered and concentrated in vacuo. The residue waswashed with EtOAc/i-Pr₂O and filtered. The filtrate was concentrated invacuo, purified by column chromatography on basic silica gel(hexane/EtOAc=50/50 to 0/100) and recrystallized with EtOAc/hexane toyield the title compound (3.57 g, 66% yield) as a pale yellow solid: ¹HNMR (DMSO-d₆, 300 MHz): δ ppm 3.83 (3H, s), 6.31 (2H, s), 7.64-7.79 (2H,m), 8.13 (2H, s), 8.64 (1H, s).

Reference Example 120 (2-Phenylfuran-3-yl)boronic acid

To a mixture of 3-bromo-2-phenylfuran (6.70 g, 30.0 mmol) and B(Oi-Pr)₃(10.4 mL, 45.0 mmol) in THF (67 mL) was added n-BuLi (1.65 M in hexane,36.4 mL, 60 mmol) at −78° C. The mixture was stirred at −78° C. for 30min and at 0° C. for 30 min. The mixture was diluted with 1 M HClaqueous solution at 0° C., extracted with EtOAc, washed with brine,dried over Na₂SO₄, filtered, concentrated in vacuo and triturated withEtOAc/hexane to yield the title compound (2.23 g, 40% yield) as a greensolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.64 (1H, d, J=1.4 Hz),7.21-7.45 (3H, m), 7.69 (1H, d, J=1.6 Hz), 8.00-8.08 (2H, m).

Reference Example 121 (2-Phenylthiophen-3-yl)boronic acid

To a mixture of 3-bromo-2-phenylthiophene (1.99 g, 8.32 mmol) andB(Oi-Pr)₃ (1.81 mL, 12.5 mmol) in THF (20 mL) was added n-BuLi (1.65 Min hexane, 10.1 mL, 16.6 mmol) at −78° C. The mixture was stirred at−78° C. for 30 min and at 0° C. for 30 min. The mixture was diluted with1 M HCl aqueous solution at 0° C., extracted with EtOAc, washed withbrine, dried over Na₂SO₄, filtered, concentrated in vacuo and purifiedby column chromatography on silica gel (hexane/EtOAc=90/10 to 0/100) toyield the title compound (87.4 mg, 5% yield) as a white solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 7.19 (1H, d, J=4.9 Hz), 7.27-7.44 (3H, m),7.46-7.58 (3H, m), 8.06 (2H, s).

Reference Example 122 Methyl4-methoxy-3-oxo-2-(pyridin-4-ylhydrazono)butanoate

4-Aminopyridine (3.6 g, 38 mmol) was added to a mixture of phosphoricacid (10 mL, 150 mmol) and nitric acid (5 mL, 78 mmol) at −6° C. Sodiumnitrite (3.2 g, 46 mmol) was added portionwise to the mixture at −6° C.,and then crushed ice (ca. 25 g) was added into the solution. Afterstirring at −6° C. for 10 min, the mixture was poured into a suspensionof methyl 4-methoxyacetoacetate (5.0 mL, 38 mmol) and sodium acetate (44g, 540 mmol) in MeOH (100 mL) at 0° C. The mixture was partitionedbetween AcOEt and water. The aqueous layer was extracted with AcOEt. Thecombined organic extract was washed with brine, dried over MgSO₄,filtered and concentrated under reduced pressure. The residual solid waswashed with AcOEt/hexane (1/3) to give the title compound (1.8 g, 19%yield) as a yellow solid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.48-3.53 (3H,m), 3.89-3.95 (3H, m), 4.64-4.69 (2H, m), 7.17-7.34 (2H, m), 8.54-8.60(2H, m), 12.65 (1H, brs).

Reference Example 123 Methyl5-methoxy-4-oxo-1-pyridin-4-yl-1,4-dihydropyridazine-3-carboxylate

A mixture of methyl 4-methoxy-3-oxo-2-(pyridin-4-ylhydrazono)butanoate(18 g, 70 mmol) and N,N-dimethylformamide dimethyl acetal (28 mL, 210mmol) in toluene (210 mL) was refluxed for 4 h. The mixture wasconcentrated under reduced pressure to give black crystals. The crystalswere washed with 2-propanol/AcOEt (1:4) to give the title compound (8.2g, 45% yield) as pale yellow crystals: ¹H NMR (300 MHz, CDCl₃): δ ppm3.99 (3H, s), 4.00 (3H, s), 7.62 (2H, dd, J=4.5, 1.5 Hz), 8.01 (1H, s),8.79 (2H, dd, J=4.5, 1.5 Hz).

Reference Example 1245-Methoxy-4-oxo-1-pyridin-4-yl-1,4-dihydropyridazine-3-carboxylic acid

To a solution of methyl5-methoxy-4-oxo-1-pyridin-4-yl-1,4-dihydropyridazine-3-carboxylate (0.50g, 1.9 mmol) in MeOH (10 mL) and THF (10 mL) was added 1 M NaOH aqueoussolution (3.0 mL, 3.0 mmol), and the mixture was stirred at roomtemperature overnight. The mixture was concentrated under reducedpressure. To the residue was added 1 M HCl aqueous solution (3.1 mL).The formed precipitate was collected by filtration, washed with waterand dried to give the title compound (0.47 g, 99% yield) as an off-whitesolid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.98 (3H, s), 7.97 (2H, dd,J=4.7, 1.7 Hz), 8.83 (2H, dd, J=4.7, 1.7 Hz), 8.92 (1H, s), 14.63 (1H,brs).

Reference Example 125 N,5-Dimethoxy-N-methyl-4-oxo-1-pyridin-4-yl-1,4-dihydropyridazine-3-carboxamide

To a mixture of5-methoxy-4-oxo-1-pyridin-4-yl-1,4-dihydropyridazine-3-carboxylic acid(8.2 g, 33 mmol), HOBt (7.6 g, 50 mmol) and WSC (9.5 g, 50 mmol) in DMF(160 mL) was added N,O-dimethylhydroxylamine hydrochloride (6.5 g, 66mmol) and TEA (14 mL, 100 mmol), and the mixture was stirred at roomtemperature overweekend. The mixture was concentrated under reducedpressure. The residue was diluted with water, saturated with K₂CO₃, andextracted with AcOEt. (There were three layers.) The highest organiclayer was dried over MgSO₄, filtered and concentrated under reducedpressure. The middle layer was extracted with CH₂Cl₂ (50 mL×4), and thecombined extracts were dried over MgSO₄, filtered and concentrated underreduced pressure. Two of the residues were combined and chromatographedon basic silica gel (0/100-10/90 MeOH/AcOEt) to give the title compound(9.6 g, 100% yield) as a pale yellow oil: ¹H NMR (300 MHz, CDCl₃): δ ppm3.40 (3H, s), 3.68 (3H, s), 3.98 (3H, s), 7.61 (2H, dd, J=4.8, 1.5 Hz),8.08 (1H, s), 8.73 (2H, dd, J=4.8, 1.5 Hz).

Reference Example 1263-Acetyl-5-methoxy-1-pyridin-4-ylpyridazin-4(1H)-one

To a solution ofN,5-dimethoxy-N-methyl-4-oxo-1-pyridin-4-yl-1,4-dihydropyridazine-3-carboxamide(9.6 g, 33 mmol) in THF (100 mL) was added dropwise 1 M MeMgBr in THF(66 mL, 66 mmol) at −78° C. for 15 min. After stirring at −78° C. for 1h, the mixture was quenched with 1 M HCl aqueous solution (70 mL). Themixture was warmed to room temperature, basified with 1 M NaOH aqueoussolution, washed with AcOEt. The aqueous layer was extracted with CH₂Cl₂(50 mL×4). The combined extract was dried over MgSO₄, filtered andconcentrated under reduced pressure to give the title compound (2.1 g,26% yield) as yellow crystals: ¹H NMR (300 MHz, CDCl₃): δ ppm 2.70 (3H,s), 3.98 (3H, s), 7.64 (2H, dd, J=4.7, 1.6 Hz), 8.04 (1H, s), 8.79 (2H,dd, J=4.7, 1.6 Hz).

Reference Example 127 Methyl5-methoxy-4-oxo-1-quinolin-8-yl-1,4-dihydropyridazine-3-carboxylate

To a suspension of quinolin-8-amine (10.0 g, 69.4 mmol) in 6 M HClaqueous solution (69.4 mL) was added a solution of NaNO₂ (5.74 g, 83.2mmol) in water (13.9 mL) at 0° C. To a suspension of methyl4-methoxy-3-oxobutanoate (8.98 mL, 69.4 mmol) and NaOAc (104 g) in EtOH(118 mL) was added the above solution at 0° C. The mixture was stirredat 0° C. for 10 min. The precipitates were collected by filtration,washed with water and EtOAc, and dried. To the solid was addedN,N-dimethylformamide dimethyl acetal (255 mL) at room temperature. Themixture was heated to reflux for 2.5 h and cooled to room temperature.The precipitates were collected by filtration, washed with hexane anddried to yield the title compound (16.6 g, 77% yield) as a gray solid:¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.77 (3H, s), 3.80 (3H, s), 7.72 (1H,dd, J=8.5, 4.0 Hz), 7.81 (1H, t, J=7.9 Hz), 8.09 (1H, d, J=7.2 Hz), 8.25(1H, d, J=8.3 Hz), 8.58 (1H, s), 8.65 (1H, s), 8.97-9.04 (1H, m).

Reference Example 1285-Methoxy-4-oxo-1-quinolin-8-yl-1,4-dihydropyridazine-3-carboxylic acid

To a suspension of methyl5-methoxy-4-oxo-1-quinolin-8-yl-1,4-dihydropyridazine-3-carboxylate(5.00 g, 16.1 mmol) in MeOH (64 mL) were added 1 M NaOH aqueous solution(64 mL) and THF (64 mL) at 0° C. The mixture was heated to 80° C. Thehomogeneous mixture was cooled to 0° C. To the mixture was added 1 M HClaqueous solution (64 mL) at 0° C. The mixture was stirred at roomtemperature for 1 h and concentrated in vacuo. The precipitates werecollected by filtration, washed with water and dried in vacuo at 60° C.to yield the title compound (3.59 g, 75% yield) as a fresh-coloredsolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.86 (3H, s), 7.73 (1H, dd,J=8.4, 4.3 Hz), 7.81-7.89 (1H, m), 8.12 (1H, dd, J=7.4, 1.4 Hz), 8.30(1H, dd, J=8.4, 1.2 Hz), 8.61 (1H, dd, J=8.5, 1.6 Hz), 8.96-9.05 (2H,m).

Reference Example 1293-Amino-5-methoxy-1-quinolin-8-ylpyridazin-4(1H)-one

A mixture of5-methoxy-4-oxo-1-quinolin-8-yl-1,4-dihydropyridazine-3-carboxylic acid(2.59 g, 8.71 mmol), DPPA (2.81 mL, 13.1 mmol) and Et₃N (1.82 mL, 13.1mmol) in toluene (26 mL) was heated to reflux for 1 h. To the suspensionwere added DMF (52 mL), DPPA (2.81 mL, 13.1 mmol) and Et₃N (1.82 mL,13.1 mmol) at room temperature. The mixture was heated to 100° C. for1.5 h. To the mixture was added 8 M NaOH aqueous solution (10.9 mL) at0° C. The mixture was stirred at room temperature for 1.5 h, extractedwith EtOAc, dried over Na₂SO₄, filtered, concentrated in vacuo, purifiedby column chromatography on basic silica gel (hexane/EtOAc=50/50 to0/100 and EtOAc/MeOH=100/0 to 80/20) and on silica gel (EtOAc/MeOH=100/0to 50/50) and triturated with EtOAc/hexane to yield the title compound(479 mg, 20% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δppm 3.75 (3H, s), 6.11 (2H, s), 7.67 (1H, dd, J=8.5, 4.4 Hz), 7.72-7.80(1H, m), 7.99 (1H, dd, J=7.6, 1.5 Hz), 8.12 (1H, dd, J=8.3, 1.1 Hz),8.48-8.61 (2H, m), 8.99 (1H, dd, J=4.4, 1.7 Hz).

Reference Example 1303-Bromo-5-methoxy-1-quinolin-8-ylpyridazin-4(1H)-one

To DMF (3 mL) were added isoamyl nitrite (0.387 mL, 2.91 mmol) and CuBr₂(299 mg, 1.34 mmol) at 0° C. To the mixture was added a solution of3-amino-5-methoxy-1-quinolin-8-ylpyridazin-4(1H)-one (300 mg, 1.12 mmol)in DMF (3 mL) at 0° C. The mixture was stirred at 0° C. for 1 h and at60° C. for 2.5 h. The mixture was diluted with water, extracted withEtOAc, washed with brine, dried over MgSO₄, filtered, concentrated invacuo, purified by column chromatography on basic silica gel(hexane/EtOAc=50/50 to 0/100 and EtOAc/MeOH=100/0 to 70/30) andtriturated with EtOAc/hexane to yield the title compound (148 mg, 41%yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.78(3H, s), 7.72 (1H, dd, J=8.3, 4.2 Hz), 7.82 (1H, t, J=8.0 Hz), 8.10 (1H,d, J=7.2 Hz), 8.25 (1H, d, J=8.3 Hz), 8.59 (1H, dd, J=8.3, 1.5 Hz), 8.73(1H, s), 9.01 (1H, dd, J=4.2, 1.5 Hz).

Reference Example 131 (1-Phenyl-1H-pyrazol-5-yl)boronic acid

To a solution of 1-phenyl-1H-pyrazole (12.8 g, 88.9 mmol) in THF (355mL) was dropwise added n-BuLi (1.63 M solution in hexane, 57.2 mL, 93.3mmol) at −78° C. under N₂. The mixture was stirred at −78° C. for 1 h.To the mixture was added B(Oi-Pr)₃ (82.0 mL, 355 mmol) at −78° C. Themixture was stirred at −78° C. for 1 h, gradually warmed to roomtemperature and stirred at room temperature overnight. The pH of themixture was adjusted to 5 with 1 M HCl aqueous solution. The mixture wasconcentrated in vacuo, extracted with EtOAc, washed with brine, driedover Na₂SO₄, filtered, concentrated in vacuo and crystallized withMeOH/EtOAc/hexane to yield the title compound (12.6 g, 76% yield) as apale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.73 (1H, brs),7.28-7.39 (1H, m), 7.39-7.54 (4H, m), 7.66 (1H, s).

Reference Example 1321-Phenyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

To a mixture of (1-phenyl-1H-pyrazol-5-yl)boronic acid (8.57 g, 45.6mmol) in toluene (86 mL) was added pinacol (5.39 g, 45.6 mmol) at roomtemperature. The mixture was heated to 40° C. for 2 days. The mixturewas concentrated in vacuo and triturated with hexane to yield the titlecompound (7.93 g, 64% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 1.23 (12H, s), 6.84 (1H, s), 7.34-7.59 (5H, m), 7.75(1H, d, J=1.9 Hz)

Reference Example 133 Methyl1-(2,2-difluoro-1,3-benzodioxol-4-yl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of sodium nitrite (1.4 g, 21 mmol) in H₂O (10 mL) was addeddropwise to a solution of 2,2-difluoro-1,3-benzodioxol-4-amine (3.0 g,17 mmol) in 6 M HCl aqueous solution (18 mL, 108 mmol) at 0° C. Afterstirring for 15 min at 0° C., the mixture was added to a suspension ofmethyl 4-methoxyacetoacetate (2.2 mL, 17 mmol) and sodium acetate (9.0g, 110 mmol) in MeOH (40 mL) pre-cooled at 0° C. The mixture waspartitioned between AcOEt and water. The organic layer was washed withbrine, dried over MgSO₄, filtered and concentrated under reducedpressure.

A solution of the residue in N,N-dimethylformamide dimethyl acetal (20mL, 150 mmol) was refluxed for 3 h. The mixture was concentrated underreduced pressure. The residual solid was washed with AcOEt/hexane (1/3)to give the title compound (4.1 g, 71% yield) as an orange solid: ¹H NMR(300 MHz, CDCl₃): δ ppm 3.96 (3H, s), 3.99 (3H, s), 7.15 (1H, dd, J=8.0,1.1 Hz), 7.23-7.30 (1H, m), 7.56 (1H, dd, J=8.5, 1.1 Hz), 8.01 (1H, s).

Reference Example 1341-(2,2-Difluoro-1,3-benzodioxol-4-yl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

To a solution of methyl1-(2,2-difluoro-1,3-benzodioxol-4-yl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(4.1 g, 12 mmol) in THF (100 mL) and MeOH (50 mL) was added 1 M NaOHaqueous solution (18 mL, 18 mmol), and the mixture was stirred at roomtemperature for 1 h. The mixture was concentrated under reducedpressure, and acidified with 1 M HCl aqueous solution. The mixture wasdiluted with AcOEt, washed with water and brine, dried over MgSO₄,filtered and concentrated under reduced pressure to give the titlecompound (3.8 g, 97% yield) as a yellow amorphous solid: ¹H NMR (300MHz, CDCl₃): δ ppm 4.06 (3H, s), 7.22-7.26 (1H, m), 7.34 (1H, t, J=8.3Hz), 7.72 (1H, dd, J=8.3, 1.1 Hz), 8.29 (1H, s).

Reference Example 135 1-(2,2-Difluoro-1,3-benzodioxol-4-yl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

To a mixture of1-(2,2-difluoro-1,3-benzodioxol-4-yl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (3.8 g, 12 mmol), HOBt (2.7 g, 17 mmol) and WSC (3.4 g, 17 mmol) inDMF (50 mL) was added N,O-dimethylhydroxylamine hydrochloride (2.3 g, 23mmol) and Et₃N (4.9 mL, 35 mmol), and the mixture was stirred at roomtemperature overnight. The mixture was diluted with water (200 mL) andextracted with AcOEt (250 mL×2). The combined organic layer was washedwith saturated NaHCO₃ aqueous solution and brine, dried over MgSO₄,filtered and concentrated under reduced pressure to give orangecrystals. The crystals were washed with AcOEt/hexane (1/4) to give thetitle compound (2.7 g, 62% yield) as pale yellow crystals: ¹H NMR (300MHz, CDCl₃): δ ppm 3.41 (3H, s), 3.71 (3H, s), 3.96 (3H, s), 7.12 (1H,dd, J=7.9, 1.1 Hz), 7.23 (1H, d, J=8.7 Hz), 7.57 (1H, dd, J=8.7, 1.1Hz), 8.06 (1H, s).

Reference Example 1363-Acetyl-1-(2,2-difluoro-1,3-benzodioxol-4-yl)-5-methoxypyridazin-4(1H)-one

To a solution of1-(2,2-difluoro-1,3-benzodioxol-4-yl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(2.7 g, 7.2 mmol) in THF (70 mL) was added dropwise 1 M MeMgBr in THF(14 mL, 14 mmol) at −78° C. for 15 min. After stirring at −78° C. for 1h, the mixture was quenched with 1 M HCl aqueous solution (30 mL). Themixture was warmed to room temperature and extracted with AcOEt. Theorganic layer was washed with brine, dried over MgSO₄, filtered andconcentrated under reduced pressure to give the title compound (2.3 g,99% yield) as yellow crystals: ¹H NMR (300 MHz, CDCl₃): δ ppm 2.69 (3H,s), 3.95 (3H, s), 7.17 (1H, dd, J=7.9, 1.1 Hz), 7.26-7.32 (1H, m), 7.55(1H, dd, J=8.7, 1.1 Hz), 8.00 (1H, s).

Reference Example 1371-(2,2-Difluoro-1,3-benzodioxol-4-yl)-3-[3-(dimethylamino)prop-2-enoyl]-5-methoxypyridazin-4(1H)-one

A solution of3-acetyl-1-(2,2-difluoro-1,3-benzodioxol-4-yl)-5-methoxypyridazin-4(1H)-one(2.3 g, 7.1 mmol) in N,N-dimethylformamide dimethyl acetal (75 mL) wasrefluxed for 3 h. The mixture was concentrated under reduced pressure.The brown crystals were washed with AcOEt/hexane (1/1) to give the titlecompound (2.0 g, 74% yield) as yellow crystals: ¹H NMR (300 MHz, CDCl₃):δ ppm 2.91 (3H, s), 3.14 (3H, s), 3.94 (3H, s), 5.78 (1H, d, J=11.7 Hz),7.10 (1H, dd, J=8.3, 1.1 Hz), 7.23 (1H, t, J=8.3 Hz), 7.63 (1H, d, J=8.7Hz), 7.79 (1H, brs), 8.03 (1H, s).

Reference Example 138 4-(Benzyloxy)-2-fluoroaniline

A suspension of 3-fluoro-4-nitrophenol (6.28 g, 40 mmol), benzyl bromide(5.00 mL, 42 mmol), and K₂CO₃ (6.63 g, 48 mmol) in acetone (80 mL) wasrefluxed for 2 h. After cooling to room temperature, the reactionmixture was poured into water and extracted with AcOEt. The extract waswashed with brine, dried over MgSO₄, and concentrated under reducedpressure. The residue was recrystallized from hexane/AcOEt to give4-(benzyloxy)-2-fluoro-1-nitrobenzene (16.0 g, 92% yield) as a paleyellow solid.

A solution of Na₂S₂O₄ (34.8 g, 200 mmol) in H₂O (200 mL) was added to amixture of 4-(benzyloxy)-2-fluoro-1-nitrobenzene (16.0 g, 64.7 mmol),THF (150 mL), and EtOH (150 mL), and the mixture was stirred for 30 minat room temperature. The reaction mixture was poured into water andextracted with AcOEt. The extract was washed with water and brine, driedover MgSO₄, and concentrated under reduced pressure. The residue waspurified by basic silica gel column chromatography eluting withhexane/AcOEt (1/1) to give the title compound (5.84 g, 42% yield) as alight brown oil: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.42 (2H, brs), 4.97(2H, s), 6.60 (1H, ddd, J=1.1, 2.6, 8.7 Hz), 6.67-6.74 (2H, m),7.28-7.43 (5H, m).

Reference Example 139 Methyl2-{[4-(benzyloxy)-2-fluorophenyl]hydrazono}-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (2.07 g, 30 mmol) in H₂O (5 mL) was added dropwiseat 0° C. to a mixture of 4-(benzyloxy)-2-fluoroaniline (5.43 g, 25 mmol)and 6 M HCl aqueous solution (25 mL, 150 mmol). After stirring for 15min, the resulting aqueous solution was added to a suspension of methyl4-methoxyacetoacetate (3.24 mL, 24 mmol) and NaOAc (12.3 g, 150 mmol) inMeOH (50 mL) pre-cooled at 0° C. The reaction mixture was poured intowater and extracted with AcOEt. The extract was washed with brine, driedover MgSO₄, and concentrated under reduced pressure. The residue wasrecrystallized from hexane/AcOEt to give the title compound (8.48 g, 91%yield) as a yellow solid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.500 (3H×0.46,s), 3.502 (3H×0.54, s), 3.88 (3H×0.54, s), 3.92 (3H×0.46, s), 4.65(2H×0.46, s), 4.68 (2H×0.54, s), 5.06 (2H×0.54, s), 5.07 (2H×0.46, s),6.75-6.86 (2H, m), 7.32-7.44 (5H, m), 7.53 (1H×0.46, t, J=9.0 Hz), 7.76(1H×0.54, t, J=9.0 Hz), 13.12 (1H×0.46, brs), 15.13 (1H×0.54, brs).

Reference Example 140 Methyl1-[4-(benzyloxy)-2-fluorophenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-{[4-(benzyloxy)-2-fluorophenyl]hydrazono}-4-methoxy-3-oxobutanoate(8.46 g, 22.6 mmol) in N,N-dimethylformamide dimethyl acetal (80 mL) wasrefluxed for 3 h. After cooling to room temperature, the reactionmixture was concentrated under reduced pressure. The residue was dilutedwith AcOEt, washed with water and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with THF and recrystallized fromhexane/THF to give the title compound (8.12 g, 93% yield) as a whitesolid: mp 143-144° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.89 (3H, s), 3.96(3H, s), 5.12 (2H, s), 6.83-6.91 (2H, m), 7.33-7.44 (5H, m), 7.48-7.54(1H, m), 7.69 (1H, d, J=2.3 Hz). Anal. Calcd for C₂₀H₁₇FN₂O₅: C, 62.50;H, 4.46; N, 7.29. Found: C, 62.40; H, 4.59; N, 7.26.

Reference Example 1411-[4-(Benzyloxy)-2-fluorophenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

To a solution of N,O-dimethylhydroxylamine hydrochloride (5.27 g, 54mmol) and iPr₂NEt (9.41 mL, 54 mmol) in CH₂Cl₂ (50 mL) was added AlMe₃(1.8 M solution in toluene, 30 mL, 54 mmol) slowly at 0° C. under Aratmosphere. After stirring for 1 h, a solution of methyl1-[4-(benzyloxy)-2-fluorophenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(8.07 g, 21 mmol) in CH₂Cl₂ (50 mL) was added slowly, and the mixturewas stirred for 1 h at 0° C. The reaction mixture was poured intoice-water and extracted with AcOEt. The extract was washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas purified by basic silica gel column chromatography eluting withAcOEt to give the title compound (7.79 g, 90% yield) as a pale yellowamorphous solid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.38 (3H, s), 3.70 (3H,s), 3.89 (3H, s), 5.11 (2H, s), 6.82-6.91 (2H, m), 7.33-7.45 (5H, m),7.48-7.55 (1H, m), 7.73 (1H, d, J=1.9 Hz).

Reference Example 1423-Acetyl-1-[4-(benzyloxy)-2-fluorophenyl]-5-methoxypyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 56.4 mL, 56.4 mmol) was added dropwise at−78° C. to a solution of1-[4-(benzyloxy)-2-fluorophenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(7.77 g, 18.8 mmol) in THF (120 mL). After stirring for 1 h, thereaction mixture was quenched with 1 M HCl aqueous solution andextracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby silica gel column chromatography eluting with AcOEt and crystallizedfrom hexane/AcOEt to give the title compound (5.86 g, 85% yield) as apale yellow solid: mp 101-103° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 2.67(3H, s), 3.89 (3H, s), 5.13 (2H, s), 6.84-6.93 (2H, m), 7.34-7.44 (5H,m), 7.48-7.55 (1H, m), 7.69 (1H, d, J=2.3 Hz). Anal. Calcd forC₂₀H₁₇FN₂O₄: C, 65.21; H, 4.65; N, 7.60. Found: C, 65.37; H, 4.68; N,7.47.

Reference Example 143 2-Fluoro-4-(trifluoromethoxy)aniline

A mixture of 4-bromo-3-fluoro(trifluoromethoxy)benzene (6.6 g, 26 mmol),benzophenone imine (6.4 mL, 38 mmol), Pd₂(dba)₃ (0.58 g, 0.64 mmol),Xantphos (1.5 g, 2.6 mmol) and sodium tert-butoxide (3.7 g, 38 mmol) in1,4-dioxane (120 mL) was stirred at 100° C. under N₂ atmosphere for 5 h.After stirring at room temperature overnight, the mixture wasconcentrated under reduced pressure. The residue was partitioned betweenAcOEt and water. The organic layer was washed with brine, dried overMgSO₄, filtered and concentrated under reduced pressure. The residue waschromatographed on silica gel (0/100-5/95 AcOEt/hexane) to give a yellowoil. The residual oil was dissolved in THF (150 mL), and 1 M HCl aqueoussolution (50 mL) was added to the mixture. After stirring at roomtemperature for 1 h, the mixture was basified with 8 M NaOH aqueoussolution and extracted with diethyl ether. The organic layer was washedwith brine, dried over MgSO₄, filtered and concentrated under reducedpressure. The residue was chromatographed on silica gel (0/100-5/95AcOEt/hexane) to give the title compound (4.2 g, 85% yield) as a paleyellow oil: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 5.36 (2H, s), 6.75-6.85(1H, m), 6.89-6.94 (1H, m), 7.12 (1H, dd, J=11.7, 2.3 Hz).

Reference Example 144 Methyl2-{[2-fluoro-4-(trifluoromethoxy)phenyl]hydrazono}-4-methoxy-3-oxobutanoate

A solution of sodium nitrite (1.9 g, 28 mmol) in H₂O (10 mL) was addeddropwise to a solution of 2-fluoro-4-(trifluoromethoxy)aniline (4.6 g,24 mmol) in 6 M HCl (24 mL, 144 mmol) at 0° C. After stirring for 15 minat 0° C., the mixture was added to a suspension of methyl4-methoxyacetoacetate (3.1 mL, 24 mmol) and sodium acetate (12 g, 144mmol) in MeOH (50 mL) pre-cooled at 0° C. The formed precipitate wascollected by filtration, washed with water and dried under reducedpressure to give the title compound (4.8 g, 58% yield) as yellowcrystals: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.51 (3H, s), 3.94 (3H, s),4.65 (2H, s), 7.06-7.14 (2H, m), 7.59-7.68 (1H, m), 12.98 (1H, brs).

Reference Example 145 Methyl1-[2-fluoro-4-(trifluoromethoxy)phenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-{[2-fluoro-4-(trifluoromethoxy)phenyl]hydrazono}-4-methoxy-3-oxobutanoate(3.8 g, 11 mmol) and N,N-dimethylformamide diisopropyl acetal (9.5 mL,54 mmol) in toluene (60 mL) was refluxed for 5 h. The mixture wasconcentrated under reduced pressure. The residue was diluted with AcOEt,washed with water and brine. The organic layer was dried over MgSO₄,filtered and concentrated under reduced pressure. The residue waschromatographed on silica gel (10/90-100/0 AcOEt/hexane) to give thetitle compound (3.4 g, 86% yield) as pale yellow crystals: ¹H NMR (300MHz, CDCl₃): δ ppm 3.91 (3H, s), 3.97 (3H, s), 7.17-7.25 (2H, m),7.68-7.76 (2H, m).

Reference Example 1461-[2-Fluoro-4-(trifluoromethoxy)phenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

To a solution of methyl1-[2-fluoro-4-(trifluoromethoxy)phenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(3.4 g, 9.3 mmol) in THF (150 mL) was added 1 M NaOH aqueous solution(14 mL, 14 mmol), and the mixture was stirred at room temperature for 30min. The mixture was acidified with 1 M HCl aqueous solution andconcentrated under reduced pressure. The residue was diluted with AcOEt,washed with water and brine, dried over MgSO₄, filtered and concentratedunder reduced pressure to give the title compound (3.2 g, 97% yield) asa pale yellow amorphous solid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.88(3H, s), 7.52-7.59 (1H, m), 7.86 (1H, dd, J=10.8, 2.5 Hz), 7.97 (1H, t,J=8.7 Hz), 8.91 (1H, d, J=1.1 Hz), 14.83 (1H, brs).

Reference Example 1473-Acetyl-1-[2-fluoro-4-(trifluoromethoxy)phenyl]-5-methoxypyridazin-4(1H)-one

To a mixture of1-[2-fluoro-4-(trifluoromethoxy)phenyl]-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (3.8 g, 11 mmol), HOBt (2.5 g, 16 mmol) and WSC (3.1 g, 16 mmol) inDMF (50 mL) was added N,O-dimethylhydroxylamine hydrochloride (2.1 g, 22mmol) and Et₃N (4.5 mL, 32 mmol), and the mixture was stirred at roomtemperature overnight. The mixture was diluted with water (200 mL) andextracted with AcOEt (250 mL×2). The combined organic layer was washedwith saturated NaHCO₃ aqueous solution and brine, dried over MgSO₄,filtered and concentrated under reduced pressure.

To a solution of the residue in THF (100 mL) was added dropwise 1 MMeMgBr in THF (18 mL, 18 mmol) at −78° C. for 15 min. After stirring at−78° C. for 1 h, the mixture was quenched with 1 M HCl aqueous solution(50 mL). The mixture was warmed to room temperature and extracted withAcOEt. The organic layer was washed with brine, dried over MgSO₄,filtered and concentrated under reduced pressure to give the titlecompound (2.8 g, 75% yield) as a yellow oil: ¹H NMR (300 MHz, CDCl₃): δppm 2.68 (3H, s), 3.91 (3H, s), 7.18-7.25 (2H, m), 7.69-7.77 (2H, m).

Reference Example 148 Methyl2-[(3-bromo-2-fluorophenyl)hydrazono]-4-methoxy-3-oxobutanoate

To a solution of tert-butyl (3-bromo-2-fluorophenyl)carbamate (7.23 g,24.9 mmol) in EtOAc (125 mL) was added 4 M HCl/EtOAc (62 mL) at 0° C.The mixture was stirred at room temperature for 12 h and concentrated invacuo. The residue was diluted with 6 M HCl aqueous solution (62 mL). Tothe suspension was added a solution of NaNO₂ (2.06 g, 29.9 mmol) inwater (5 mL) at 0° C. To a suspension of methyl 4-methoxy-3-oxobutanoate(3.22 mL, 24.9 mmol) and NaOAc (92.9 g) in EtOH (84 mL) was added theabove mixture at 0° C. The mixture was stirred at 0° C. for 20 min. Theprecipitates were collected by filtration, diluted with EtOAc, washedwith NaHCO₃ aqueous solution, dried over MgSO₄, filtered andconcentrated in vacuo to yield the title compound (5.36 g, 62% yield) asa brown solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.30 (3H, s), 3.75-3.94(3H, m), 4.56-4.71 (2H, m), 7.15-7.34 (1H, m), 7.37-7.59 (1H, m),7.63-7.80 (1H, m), 12.26 (1H, s).

Reference Example 149 Methyl1-(3-bromo-2-fluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A mixture of methyl2-[(3-bromo-2-fluorophenyl)hydrazono]-4-methoxy-3-oxobutanoate (5.36 g,15.4 mmol) in N,N-dimethylformamide dimethyl acetal (54 mL) was heatedto reflux for 2 h and cooled to 0° C. The precipitates were collected byfiltration, washed with hexane and dried to yield the title compound(4.16 g, 75% yield) as a brown solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm3.80 (3H, s), 3.83 (3H, s), 7.40 (1H, td, J=8.1, 1.1 Hz), 7.75-7.84 (1H,m), 7.94 (1H, ddd, J=8.1, 6.4, 1.7 Hz), 8.60 (1H, d, J=1.9 Hz).

Reference Example 1501-(3-Bromo-2-fluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

To a suspension of methyl1-(3-bromo-2-fluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(4.16 g, 11.7 mmol) in MeOH (46 mL) was added 1 M NaOH aqueous solution(23 mL) at 0° C. The mixture was stirred at room temperature for 1 h. Tothe solution was added 1 M HCl aqueous solution (23 mL) at 0° C. Themixture was concentrated in vacuo. The precipitates were collected byfiltration, washed with water and dried in vacuo at 50° C. to yield thetitle compound (3.76 g, 94% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.87 (3H, s), 7.43 (1H, td, J=8.1, 1.5 Hz),7.76-7.85 (1H, m), 7.98 (1H, ddd, J=8.0, 6.5, 1.3 Hz), 8.86 (1H, s),14.84 (1H, brs).

Reference Example 1511-(3-Bromo-2-fluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(3-bromo-2-fluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (3.76 g, 11.0 mmol) and CDI (1.95 g, 12.1 mmol) in THF (38 mL) washeated to 40° C. for 2 h. To the solution were addedN,O-dimethylhydroxylamine hydrochloride (1.60 g, 16.4 mmol) and i-Pr₂NEt(2.86 mL, 16.4 mmol) at room temperature. The mixture was stirred atroom temperature for 18 h. The mixture was diluted with water and 1 MHCl aqueous solution, extracted with EtOAc, dried over Na₂SO₄, filtered,concentrated in vacuo and purified by column chromatography on basicsilica gel (EtOAc/MeOH=100/0 to 80/20) to yield the title compound (4.22g, >99% yield) as a white solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.25(3H, s), 3.58 (3H, s), 3.80 (3H, s), 7.39 (1H, td, J=8.1, 1.5 Hz), 7.78(1H, ddd, J=8.2, 6.9, 1.5 Hz), 7.92 (1H, ddd, J=8.0, 6.3, 1.5 Hz), 8.58(1H, s).

Reference Example 1523-Acetyl-1-(3-bromo-2-fluorophenyl)-5-methoxypyridazin-4(1H)-one

To a solution of1-(3-bromo-2-fluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(4.22 g, 10.9 mmol) in THF (218 mL) was added MeMgBr (1.0 M in THF, 16.4mL, 16.4 mmol) at −78° C. under N₂. The mixture was stirred at −78° C.for 2 h. The reaction was quenched with saturated NH₄Cl aqueous solutionat −78° C. The mixture was diluted with NaHCO₃ aqueous solution,extracted with EtOAc, dried over Na₂SO₄, filtered, concentrated in vacuoand purified by column chromatography on silica gel (EtOAc/MeOH=100/0 to50/50) to yield the title compound (3.48 g, 93% yield) as a yellowsolid: ¹H-NMR (DMSO-d₆, 300 MHz): δ ppm 2.50 (3H, s), 3.80 (3H, s),7.36-7.46 (1H, m), 7.77-7.85 (1H, m), 7.89-7.99 (1H, m), 8.57 (1H, d,J=1.9 Hz).

Reference Example 153 Methyl4-methoxy-3-oxo-2-[(2,2,6-trifluoro-1,3-benzodioxol-5-yl)hydrazono]butanoate

To a suspension of 2,2,6-trifluoro-1,3-benzodioxol-5-amine (4.95 g, 25.9mmol) in 6 M HCl aqueous solution (25.9 mL) was added a solution ofNaNO₂ (2.15 g, 31.1 mmol) in water (5.2 mL) at 0° C. To a suspension ofmethyl 4-methoxy-3-oxobutanoate (3.35 mL, 25.9 mmol) and NaOAc (38.9 g)in EtOH (44 mL) was added the above solution at 0° C. The mixture wasstirred at 0° C. for 10 min. The precipitates were collected byfiltration, washed with water, dissolved in EtOAc, washed with brine andNaHCO₃ aqueous solution, dried over MgSO₄, filtered and concentrated invacuo to yield the title compound (6.31 g, 70% yield) as a red solid: ¹HNMR (DMSO-d₆, 300 MHz): δ ppm 3.33 (3H, s), 3.82 (3H, s), 4.66 (2H, s),7.57-7.92 (2H, m), 12.32 (1H, brs).

Reference Example 154 Methyl5-methoxy-4-oxo-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)-1,4-dihydropyridazine-3-carboxylate

A mixture of methyl4-methoxy-3-oxo-2-[(2,2,6-trifluoro-1,3-benzodioxol-5-yl)hydrazono]butanoate(6.31 g, 18.1 mmol) in N,N-dimethylformamide dimethyl acetal (63 mL) washeated to reflux for 2.5 h. The mixture was concentrated in vacuo andpurified by column chromatography on silica gel (hexane/EtOAc=5 0/50 to0/100 and EtOAc/MeOH=100/0 to 70/30) and on basic silica gel(hexane/EtOAc=50/50 to 0/100) to yield the title compound (1.53 g, 24%yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.79(3H, s), 3.82 (3H, s), 7.94 (1H, d, J=9.4 Hz), 8.04 (1H, d, J=6.4 Hz),8.54 (1H, s).

Reference Example 1555-Methoxy-4-oxo-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)-1,4-dihydropyridazine-3-carboxylicacid

To a suspension of methyl5-methoxy-4-oxo-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)-1,4-dihydropyridazine-3-carboxylate(1.53 g, 4.27 mmol) in MeOH (17 mL) was added 1 M NaOH aqueous solution(8.5 mL) at 0° C. The mixture was stirred at room temperature for 30min. To the mixture was added 1 M HCl aqueous solution (8.5 mL) at 0° C.The mixture was concentrated in vacuo. The precipitates were collectedby filtration, washed with water and dried in vacuo at 60° C. to yieldthe title compound (1.18 g, 80% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.86 (3H, s), 7.98 (1H, d, J=9.4 Hz), 8.03(1H, d, J=6.4 Hz), 8.79 (1H, s), 14.77 (1H, brs).

Reference Example 1563-Amino-5-methoxy-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)pyridazin-4(1H)-one

A mixture of5-methoxy-4-oxo-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)-1,4-dihydropyridazine-3-carboxylicacid (1.18 g, 3.42 mmol), DPPA (1.10 mL, 5.13 mmol) and Et₃N (0.715 mL,5.13 mmol) in toluene (12 mL) was heated to 100° C. for 1 h. To themixture was added 8 M NaOH aqueous solution (4.3 mL) at 0° C. Themixture was stirred at room temperature for 1 h, extracted with EtOAc,dried over Na₂SO₄, filtered, concentrated in vacuo and purified bycolumn chromatography on basic silica gel (hexane/EtOAc=50/50 to 0/100)and recrystallized with EtOAc/hexane to yield the title compound (704mg, 65% yield) as a white solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.73(3H, s), 6.21 (2H, s), 7.85 (1H, d, J=9.4 Hz), 7.90 (1H, d, J=6.4 Hz),8.33 (1H, s).

Reference Example 1573-Bromo-5-methoxy-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)pyridazin-4(1H)-one

To a mixture of isoamyl nitrite (0.22 mL, 1.65 mmol) and CuBr₂ (0.17 g,0.762 mmol) in DMF (2 mL) was added a mixture of3-amino-5-methoxy-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)pyridazin-4(1H)-one(200 mg, 0.635 mmol) in DMF (4 mL) at 0° C. The mixture was stirred at0° C. for 1 h and at 60° C. for 2 h. The mixture was diluted with waterand brine, extracted with EtOAc, dried over Na₂SO₄, filtered,concentrated in vacuo and purified by column chromatography on silicagel (hexane/EtOAc=50/50 to 0/100) to yield the title compound (145 mg,60% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.79(3H, s), 7.93 (1H, d, J=9.5 Hz), 8.02 (1H, d, J=6.4 Hz), 8.59 (1H, d,J=1.5 Hz).

Reference Example 158 Methyl4-methoxy-3-oxo-2-[(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)hydrazono]butanoate

To a suspension of2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-amine (4.87 g, 20.2mmol) in 6 M HCl aqueous solution (20.2 mL) was added a solution ofNaNO₂ (1.67 g, 24.2 mmol) in water (4 mL) at 0° C. The mixture wasstirred at 0° C. for 15 min. To a suspension of methyl4-methoxy-3-oxobutanoate (2.61 mL, 20.2 mmol) and NaOAc (30.3 g) in EtOH(34 mL) was added the above solution at 0° C. The mixture was stirred at0° C. for 15 min. The precipitates were collected by filtration, washedwith water, dissolved in EtOAc, washed with brine, dried over MgSO₄,filtered and concentrated in vacuo to yield the title compound (6.84 g,85% yield) as a red solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.33 (3H,s), 3.82 (3H, s), 4.68 (2H, s), 7.66-7.93 (2H, m), 12.16 (1H, brs).

Reference Example 159 Methyl5-methoxy-4-oxo-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)-1,4-dihydropyridazine-3-carboxylate

A mixture of methyl4-methoxy-3-oxo-2-[(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)hydrazono]butanoate(6.84 g, 17.2 mmol) in N,N-dimethylformamide dimethyl acetal (68 mL) washeated to reflux for 2.5 h. The mixture was concentrated in vacuo,diluted with brine, extracted with EtOAc, dried over MgSO₄, filtered,concentrated in vacuo and purified by column chromatography on silicagel (hexane/EtOAc=50/50 to 0/100 and EtOAc/MeOH=100/0 to 70/30) and onbasic silica gel (hexane/EtOAc=80/20 to 0/100 and EtOAc/MeOH=100/0 to70/30) to yield the title compound (2.58 g, 37% yield) as a pale yellowsolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.79 (3H, s), 3.83 (3H, s), 8.01(1H, d, J=10.2 Hz), 8.16 (1H, d, J=7.2 Hz), 8.58 (1H, s).

Reference Example 1605-Methoxy-4-oxo-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)-1,4-dihydropyridazine-3-carboxylicacid

To a solution of methyl5-methoxy-4-oxo-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)-1,4-dihydropyridazine-3-carboxylate(2.58 g, 6.31 mmol) in MeOH (26 mL) was added 1 M NaOH aqueous solution(13 mL) at 0° C. The mixture was stirred at room temperature for 90 min.To the mixture was added 1 M HCl aqueous solution (13 mL) at 0° C. Themixture was concentrated in vacuo. The precipitates were collected byfiltration, washed with water and dried in vacuo at 60° C. to yield thetitle compound (2.33 g, 94% yield) as a white solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 3.86 (3H, s), 8.06 (1H, d, J=10.2 Hz), 8.17 (1H, d,J=6.8 Hz), 8.82 (1H, s), 14.66 (1H, brs).

Reference Example 1613-Amino-5-methoxy-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)pyridazin-4(1H)-one

A mixture of5-methoxy-4-oxo-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)-1,4-dihydropyridazine-3-carboxylicacid (2.33 g, 5.91 mmol), DPPA (1.90 mL, 8.86 mmol) and Et₃N (1.23 mL,8.86 mmol) in toluene (23 mL) was heated to 100° C. for 90 min. To themixture was added 8 M NaOH aqueous solution (7.4 mL) at 0° C. Themixture was stirred at room temperature for 2 h, extracted with EtOAc,dried over Na₂SO₄, filtered, concentrated in vacuo, purified by columnchromatography on basic silica gel (hexane/EtOAc=50/50 to 0/100) and onsilica gel (hexane/EtOAc=80/20 to 0/100) and triturated withEtOAc/hexane to yield the title compound (1.12 g, 53% yield) as a whitesolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.73 (3H, s), 6.24 (2H, s), 7.92(1H, d, J=10.5 Hz), 7.99 (1H, d, J=6.8 Hz), 8.37 (1H, d, J=1.5 Hz).

Reference Example 1623-Bromo-5-methoxy-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)pyridazin-4(1H)-one

To a mixture of isoamyl nitrite (0.473 mL, 3.56 mmol) and CuBr₂ (367 mg,1.64 mmol) in DMF (5 mL) was added a mixture of3-amino-5-methoxy-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)pyridazin-4(1H)-one(500 mg, 1.37 mmol) in DMF (2.5 mL) at 0° C. The mixture was stirred at0° C. for 1 h and at 60° C. for 2.5 h. The mixture was diluted withwater and brine, extracted with EtOAc, dried over MgSO₄, filtered,concentrated in vacuo, purified by column chromatography on silica gel(hexane/EtOAc=50/50 to 0/100) and crystallized with EtOH/hexane to yieldthe title compound (381 mg, 65% yield) as a white solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.79 (3H, s), 8.02 (1H, d, J=10.5 Hz), 8.14(1H, d, J=6.8 Hz), 8.63 (1H, s).

Reference Example 1631-[2-Fluoro-3-(1-methyl-1H-pyrazol-4-yl)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(3-bromo-2-fluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(500 mg, 1.29 mmol),1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole(295 mg, 1.42 mmol), Na₂CO₃ (302 mg, 2.85 mmol) and Pd(PPh₃)₄(74.5 mg,0.0645 mmol) in DME (11.4 mL) and water (2.9 mL) was heated to refluxfor 15 h under Ar. The mixture was diluted with water, extracted withEtOAc, washed with brine, dried over Na₂SO₄, filtered, concentrated invacuo, and purified by column chromatography on basic silica gel(EtOAc/MeOH=100/0 to 70/30) to yield the title compound (345 mg, 69%yield) as a white solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.25 (3H, s),3.59 (3H, s), 3.80 (3H, s), 3.90 (3H, s), 7.35-7.44 (1H, m), 7.50-7.59(1H, m), 7.84-7.94 (1H, m), 7.97 (1H, s), 8.23 (1H, d, J=2.5 Hz), 8.58(1H, s).

Reference Example 1643-Acetyl-1-[2-fluoro-3-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxypyridazin-4(1H)-one

To a solution of1-[2-fluoro-3-(1-methyl-1H-pyrazol-4-yl)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(345 mg, 0.890 mmol) in THF (100 mL) was added MeMgBr (1.0 M in THF,2.67 mL, 2.67 mmol) at −78° C. under N₂. The mixture was stirred at −78°C. for 100 min. The reaction was quenched with saturated NH₄Cl aqueoussolution at −78° C. The mixture was extracted with EtOAc, dried overNa₂SO₄, filtered, concentrated in vacuo and purified by columnchromatography on silica gel (EtOAc/MeOH=100/0 to 70/30) to yield thetitle compound (243 mg, 80% yield) as a white solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 2.51 (3H, brs), 3.81 (3H, s), 3.91 (3H, s), 7.38-7.46(1H, m), 7.54-7.64 (1H, m), 7.86-7.95 (1H, m, J=15.0, 1.7 Hz), 7.98 (1H,s), 8.25 (1H, d, J=2.3 Hz), 8.58 (1H, d, J=1.9 Hz).

Reference Example 165 Methyl2-[(2-fluoro-5-iodophenyl)hydrazono]-4-methoxy-3-oxobutanoate

To a suspension of 2-fluoro-5-iodoaniline (9.83 g, 41.5 mmol) in 6 M HClaqueous solution (83.0 mL) was added a solution of NaNO₂ (3.43 g, 49.8mmol) in water (8.3 mL) at 0° C. To a suspension of methyl4-methoxy-3-oxobutanoate (5.37 mL, 41.5 mmol) and NaOAc (124 g) in EtOH(70 mL) was added the above solution at 0° C. The mixture was stirred at0° C. for 10 min. The precipitates were collected by filtration, washedwith water, dissolved in EtOAc, washed with brine, dried over MgSO₄,filtered and concentrated in vacuo to yield the title compound (14.2 g,87% yield) as a red solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.31 (3H,s), 3.83 (3H, s), 4.64 (2H, s), 7.03-7.41 (1H, m), 7.43-7.66 (1H, m),7.85-8.07 (1H, m), 12.20 (1H, brs).

Reference Example 166 Methyl1-(2-fluoro-5-iodophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A mixture of methyl2-[(2-fluoro-5-iodophenyl)hydrazono]-4-methoxy-3-oxobutanoate (14.2 g,35.9 mmol) in N,N-dimethylformamide dimethyl acetal (142 mL) was heatedto reflux for 1.5 h and cooled to 0° C. The precipitates were collectedby filtration, washed with hexane and dried to yield the title compound(11.3 g, 78% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δppm 3.80 (3H, s), 3.82 (3H, s), 7.37 (1H, dd, J=10.6, 8.7 Hz), 7.90-8.01(1H, m), 8.14 (1H, dd, J=7.2, 2.3 Hz), 8.55 (1H, s).

Reference Example 1671-(2-Fluoro-5-iodophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

To a suspension of methyl1-(2-fluoro-5-iodophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(11.3 g, 28.1 mmol) in MeOH (112 mL) was added 1 M NaOH aqueous solution(56 mL) at 0° C. The mixture was stirred at room temperature for 90 min.To the mixture was added 1 M HCl aqueous solution (56 mL) at 0° C. Themixture was concentrated in vacuo. The precipitates were collected byfiltration, washed with water and dried in vacuo at 60° C. to yield thetitle compound (9.96 g, 91% yield) as a yellow solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 3.88 (3H, s), 7.42 (1H, dd, J=10.6, 8.7 Hz), 8.00 (1H,ddd, J=8.7, 4.5, 2.3 Hz), 8.16 (1H, dd, J=7.2, 2.3 Hz), 8.85 (1H, s),14.86 (1H, brs).

Reference Example 1681-(2-Fluoro-5-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(2-fluoro-5-iodophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (9.96 g, 25.5 mmol) and CDI (4.55 g, 28.1 mmol) in THF (200 mL) washeated to 40° C. for 30 min and 50° C. for 90 min. To the mixture wasadded DMF (20 mL). The mixture was stirred at 50° C. for 70 min. To thesolution were added N,O-dimethylhydroxylamine hydrochloride (3.74 g,38.3 mmol) and i-Pr₂NEt (6.67 mL, 38.3 mmol) at room temperature. Thesolution was stirred at room temperature for 16 h. The mixture wasconcentrated in vacuo, diluted with water and 1 M HCl aqueous solution,extracted with EtOAc, washed with saturated NaHCO₃ aqueous solution,dried over Na₂SO₄, filtered, concentrated in vacuo and purified bycolumn chromatography on silica gel (hexane/EtOAc=20/80 to 0/100 andEtOAc/MeOH=100/0 to 0/100) and triturated with MeOH/EtOH/hexane to yieldthe title compound (9.11 g, 82% yield) as a pale yellow solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.24 (3H, s), 3.56 (3H, s), 3.80 (3H, s), 7.36(1H, dd, J=10.6, 8.7 Hz), 7.93 (1H, ddd, J=8.7, 4.5, 2.3 Hz), 8.12 (1H,dd, J=7.4, 2.1 Hz), 8.53 (1H, s).

Reference Example 1691-[2-Fluoro-5-(1-methyl-1H-pyrazol-4-yl)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(2-fluoro-5-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(500 mg, 1.15 mmol),1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole(264 mg, 1.27 mmol), Na₂CO₃ (268 mg, 2.53 mmol) and Pd(PPh₃)₄(66.4 mg,0.0575 mmol) in DME (10.1 mL) and water (2.5 mL) was heated to refluxfor 14 h under Ar. The mixture was diluted with water, brine andsaturated NaHCO₃ aqueous solution, extracted with EtOAc, dried overNa₂SO₄, filtered, concentrated in vacuo, and purified by columnchromatography on basic silica gel (hexane/EtOAc=50/50 to 0/100 andEtOAc/MeOH=100/0 to 60/40) to yield the title compound (267 mg, 60%yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.25(3H, s), 3.59 (3H, s), 3.82 (3H, s), 3.87 (3H, s), 7.51 (1H, dd, J=10.4,8.9 Hz), 7.73-7.80 (1H, m), 7.89-7.97 (2H, m), 8.23 (1H, s), 8.58 (1H,s).

Reference Example 1703-Acetyl-1-[2-fluoro-5-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxypyridazin-4(1H)-one

To a mixture of1-[2-fluoro-5-(1-methyl-1H-pyrazol-4-yl)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(267 mg, 0.687 mmol) in THF (80 mL) was added MeMgBr (1.0 M in THF, 2.06mL, 2.06 mmol) at −78° C. under N₂. The mixture was stirred at −78° C.for 2 h. To the mixture was added MeMgBr (1.0 M in THF, 0.687 mL, 0.687mmol) at −78° C. The mixture was stirred at −78° C. for 1 h. To themixture was added MeMgBr (1.0 M in THF, 1.37 mL, 1.37 mmol) at −78° C.The mixture was stirred at −78° C. for 3 h. The reaction was quenchedwith saturated NH₄Cl aqueous solution at −78° C. The mixture was dilutedwith saturated NaHCO₃ aqueous solution, extracted with EtOAc, dried overNa₂SO₄, filtered, concentrated in vacuo and purified by columnchromatography on silica gel (EtOAc/MeOH=100/0 to 70/30) to yield thetitle compound (201 mg, 85% yield) as a yellow solid: ¹H NMR (DMSO-d₆,300 MHz): δ ppm 2.52 (3H, s), 3.82 (3H, s), 3.87 (3H, s), 7.53 (1H, dd,J=10.6, 8.7 Hz), 7.78 (1H, ddd, J=8.7, 4.5, 2.3 Hz), 7.92-8.00 (2H, m),8.23 (1H, s), 8.56 (1H, d, J=1.5 Hz).

Reference Example 171 1-(Difluoromethyl)-1H-pyrazole-4-boronic acidpinacol ester

A suspension of 1H-pyrazole-4-boronic acid pinacol ester (5.16 g, 26.6mmol), CF₂ClCO₂Na (4.86 g, 31.9 mmol), and 18-crown-6 (1.41 g, 5.32mmol) in CH₃CN (100 mL) was refluxed for 20 h. After cooling to roomtemperature, the reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with AcOEt to give the titlecompound (3.03 g, 47% yield) as a yellow oil: ¹H NMR (300 MHz, CDCl₃): δppm 1.33 (12H, s), 7.22 (1H, t, J=60.7 Hz), 7.89 (1H, s), 8.13 (1H, s).

Reference Example 172 tert-Butyl1-{3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}hydrazinecarboxylate

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(2.44 g, 5.0 mmol), tert-butyl carbazate (0.727 g, 5.5 mmol), CuI(0.0095 g, 0.05 mmol), 1,10-phenanthroline (0.072 g, 0.4 mmol), andCs₂CO₃ (2.28 g, 7.0 mmol) in DMF (25 mL) was stirred for 5 h at 100° C.under Ar atmosphere. After cooling to room temperature, the reactionmixture was poured into water and extracted with AcOEt three times. Thecombined extracts were washed with water and brine, dried over MgSO₄,and concentrated under reduced pressure. The residue was purified bybasic silica gel column chromatography eluting with AcOEt andcrystallized from hexane/AcOEt to give the title compound (2.04 g, 83%yield) as a pale yellow solid: mp 163-165° C.; ¹H NMR (300 MHz, CDCl₃):δ ppm 1.58 (9H, s), 3.90 (3H, s), 4.36 (2H, s), 6.31 (1H, t, J=9.0 Hz),7.28-7.45 (7H, m), 7.55 (1H, dd, J=2.3, 14.3 Hz), 7.78 (2H, d, J=1.9Hz). Anal. Calcd for C₂₅H₂₅FN₆O₄: C, 60.97; H, 5.12; N, 17.06. Found: C,61.20; H, 5.13; N, 16.81.

Reference Example 1733-{[2-(1-Methylethyl)phenyl]hydrazono}pentane-2,4-dione

2-(1-Methylethyl)aniline (2.00 g, 14.81 mmol) was added to a solution of12 mL of phosphoric acid (85%) and 8 mL of nitric acid (65%) at −6° C.,followed by sodium nitrite (1.23 g, 17.78 mmol) in 4 mL of waterdropwise at 0° C., and the mixture was stirred at 0° C. for 30 min.Then, to the reaction mixture was added dropwise a solution of potassiumacetate (4.35 g, 44.43 mmol) and acetylacetone (1.92 g, 19.25 mmol) in80 mL of ethanol and 20 mL of water. The mixture was stirred at roomtemperature overnight, filtered, washed with water, EtOH/H₂O (1/1) andhexane, and dried to give the title compound (0.98 g, 27% yield): ¹H NMR(400 MHz, CDCl₃): δ ppm 1.34 (6H, d, J=6.8 Hz), 2.52 (3H, s), 2.63 (3H,s), 3.12-3.21 (1H, m), 7.19-7.23 (1H, m), 7.28-7.34 (2H, m), 7.77-8.00(1H, m), 15.23 (1H, brs).

Reference Example 1742-[2-(1-Acetyl-2-oxopropylidene)hydrazino]benzonitrile

2-Aminobenzonitrile (5.00 g, 42.37 mmol) was added to a solution of 30mL of phosphoric acid (85%) and 20 mL of nitric acid (65%) at −6° C.,followed by sodium nitrite (3.50 g, 50.78 mmol) in 10 mL of waterdropwise at 0° C., and the mixture was stirred at 0° C. for 30 min.Then, to the reaction mixture was added dropwise a solution of potassiumacetate (12.45 g, 127.11 mmol) and acetylacetone (5.51 g, 55.08 mmol) in80 mL of ethanol and 48 mL of water. The mixture was stirred at roomtemperature overnight, filtered, washed with water, EtOH/H₂O (1/1) andhexane, and dried to give the title compound (4.00 g, 41% yield): ¹H NMR(400 MHz, CDCl₃): δ ppm 2.50 (3H, s), 2.63 (3H, s), 7.21-7.25 (1H, m),7.62-7.66 (2H, m), 7.77-7.79 (1H, m), 15.01 (1H, s).

Reference Example 175 3-(Biphenyl-2-ylhydrazono)pentane-2,4-dione

Biphenyl-2-amine (500 mg, 2.96 mmol) was added to a solution of 3 mL ofphosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C., followedby sodium nitrite (254 mg, 3.55 mmol) in 1 mL of water dropwise at 0°C., and the mixture was stirred at 0° C. for 30 min. Then, to thereaction mixture was added dropwise a solution of potassium acetate (870mg, 8.88 mmol) and acetylacetone (385 mg, 3.85 mmol) in 60 mL of ethanoland 32 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1/1) and hexane, anddried to give the title compound (420 mg, 51% yield): ¹H NMR (400 MHz,CDCl₃): δ ppm 2.51 (3H, s), 2.52 (3H, s), 7.29-7.60 (9H, m), 14.63 (1H,s).

Reference Example 176 3-[(2-Ethoxyphenyl)hydrazono]pentane-2,4-dione

2-Ethoxyaniline (2.00 g, 14.60 mmol) was added to a solution of 12 mL ofphosphoric acid (85%) and 8 mL of nitric acid (65%) at −6° C., followedby sodium nitrite (1.21 g, 17.52 mmol) in 10 mL of water dropwise at 0°C., and the mixture was stirred at 0° C. for 30 min. Then, to thereaction mixture was added dropwise a solution of potassium acetate(4.29 g, 43.80 mmol) and acetylacetone (1.90 g, 18.98 mmol) in 60 mL ofethanol and 25 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1/1) and hexane, anddried to give the title compound (2.00 g, 55% yield): ¹H NMR (400 MHz,CDCl₃): δ ppm 1.57 (3H, t, J=7.2 Hz), 2.53 (3H, s), 2.63 (3H, s), 4.20(2H, t, J=7.2 Hz), 7.03-7.07 (1H, m), 7.14-7.18 (1H, m), 7.74-7.84 (2H,m), 14.86 (1H, s).

Reference Example 1773-{[2-(1-Methylethoxy)phenyl]hydrazono}pentane-2,4-dione

2-(1-Methylethoxy)aniline (1.00 g, 6.62 mmol) was added to a solution of6 mL of phosphoric acid (85%) and 4 mL of nitric acid (65%) at −6° C.,followed by sodium nitrite (0.55 g, 7.95 mmol) in 2 mL of water dropwiseat 0° C., and the mixture was stirred at 0° C. for 30 min. Then, to thereaction mixture was added dropwise a solution of potassium acetate(1.95 g, 19.86 mmol) and acetylacetone (0.86 g, 8.61 mmol) in 40 mL ofethanol and 10 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1/1) and hexane, anddried to give the title compound (0.53 g, 30% yield): ¹H NMR (400 MHz,CDCl₃): δ ppm 1.28-1.41 (6H, m), 2.50 (3H, s), 2.63 (3H, s), 4.53-4.59(1H, m), 7.21-7.25 (1H, m), 7.62-7.66 (2H, m), 7.77-7.79 (1H, m), 15.01(1H, s).

Reference Example 1783-{[2-(Trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

2-(Trifluoromethoxy)aniline (1.00 g, 5.64 mmol) was added to a solutionof 6 mL of phosphoric acid (85%) and 4 mL of nitric acid (65%) at −6°C., followed by sodium nitrite (389 mg, 5.64 mmol, 1.0 equiv.) in 2 mLof water dropwise at 0° C., and the mixture was stirred at 0° C. for 30min. Then to the reaction mixture was added dropwise a mixture ofpotassium acetate (1.66 g, 16.92 mmol) and acetylacetone (564 mg, 5.64mmol) in 80 mL of ethanol and 48 mL of water. The mixture was stirred atroom temperature overnight, filtered, washed with water, EtOH/H₂O (1/1)and hexane, and dried to give the title compound (1.3 g, 80% yield): ¹HNMR (400 MHz, CDCl₃): δ ppm 2.54 (s, 3H), 2.65 (s, 3H), 7.20-7.24 (m,1H), 7.33-7.42 (m, 2H), 7.87 (dd, J=8.4, 1.6 Hz, 1H), 14.86 (s, 1H).

Reference Example 179 3-[(2-Phenoxyphenyl)hydrazono]pentane-2,4-dione

2-Phenoxyaniline (2.00 g, 10.81 mmol) was added to a solution of 12 mLof phosphoric acid (85%) and 8 mL of nitric acid (65%) at −6° C.,followed by sodium nitrite (0.90 g, 12.97 mmol) in 2 mL of waterdropwise at 0° C., and the mixture was stirred at 0° C. for 30 min.Then, to the reaction mixture was added dropwise a mixture of potassiumacetate (3.18 g, 32.43 mmol) and acetylacetone (1.40 g, 14.05 mmol) in80 mL of ethanol and 48 mL of water. The mixture was stirred at roomtemperature overnight, filtered, washed with water, EtOH/H₂O (1/1) andhexane, and dried to give the title compound (1.00 g, 31% yield): ¹H NMR(400 MHz, CDCl₃): δ ppm 2.50 (3H, s), 2.63 (3H, s), 7.26-7.88 (9H, m),14.91 (1H, s).

Reference Example 1803-{[2-(Methylsulfinyl)phenyl]hydrazono}pentane-2,4-dione

2-(Methylsulfinyl)aniline (0.50 g, 3.22 mmol) was added to a solution of3 mL of phosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C.,followed by sodium nitrite (0.27 g, 3.87 mmol) in 2 mL of water dropwiseat 0° C., and the mixture was stirred at 0° C. for 30 min. Then, to thereaction mixture was added dropwise a mixture of potassium acetate (0.95g, 9.66 mmol) and acetylacetone (0.42 g, 4.19 mmol) in 80 mL of ethanoland 48 mL of water. The mixture was stirred at room temperatureovernight, filtered, washed with water, EtOH/H₂O (1/1) and hexane, anddried to give the title compound (0.66 g, 77% yield): ¹H NMR (400 MHz,CDCl₃): δ ppm 2.07 (3H, s), 2.55 (3H, s), 2.64 (3H, s), 7.29-7.87 (4H,m), 15.06 (1H, s).

Reference Example 1813-{[3-(Trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

3-(Trifluoromethoxy)aniline (1.00 g, 5.64 mmol) was added to a solutionof 6 mL of phosphoric acid (85%) and 4 mL of nitric acid (65%) at −6°C., followed by sodium nitrite (389 mg, 5.64 mmol) in 2 mL of waterdropwise at 0° C., and the mixture was stirred at 0° C. for 30 min. Thento the reaction mixture was added dropwise a mixture of potassiumacetate (1.66 g, 16.92 mmol) and acetylacetone (564 mg, 5.64 mmol) in 80mL of ethanol and 48 mL of water. The mixture was stirred at roomtemperature overnight, filtered, washed with water, EtOH/H₂O (1/1) andhexane, and dried to give the title compound (1.2 g, 74% yield): ¹H NMR(400 MHz, CDCl₃): δ ppm 2.49 (s, 3H), 2.61 (s, 3H), 7.05-7.08 (m, 1H),7.25-7.27 (m, 1H), 7.32 (s, 1H), 7.42 (t, J=8.0 Hz, 1H), 14.59 (s, 1H).

Reference Example 182N-{4-[2-(1-Acetyl-2-oxopropylidene)hydrazino]phenyl}acetamide

N-(4-Aminophenyl)acetamide (1000 mg, 6.66 mmol) was added to a solutionof 6 mL of phosphoric acid (85%) and 4 mL of nitric acid (65%) at −6° C.When the mixture reached to room temperature, it was cooled to −6° C.and solid sodium nitrite (460 mg, 6.66 mmol) was added during 10 min.Small piece of ice (50 g) was added into the solution. The mixture wasadded at 0° C. to a suspension of 2,4-pentanedione (666 mg, 6.66 mmol)and potassium acetate (40 g) in ethanol (400 mL). The solution wasstirred for 15 min, and then was added to 250 mL of saturated Na₂CO₃aqueous solution, extracted with dichloromethane, washed with water andbrine, dried over Na₂SO₄, and concentrated under reduced pressure togive the title compound (1400 mg, 80% yield): ¹H NMR (400 MHz, CDCl₃): δppm 2.22 (3H, s), 2.48 (3H, s), 2.60 (3H, s), 7.22 (1H, brs), 7.38 (2H,d, J=8.8 Hz), 7.57 (2H, d, J=8.8 Hz), 14.84 (1H, s).

Reference Example 1833-{[4-(Dimethylamino)phenyl]hydrazono}pentane-2,4-dione

N,N-Dimethylbenzene-1,4-diamine (500 mg, 3.67 mmol) was added to asolution of 3 mL of phosphoric acid (85%) and 2 mL of nitric acid (65%)at −6° C. When the mixture reached to room temperature, it was cooled to−6° C. and sodium nitrite (253 mg, 3.67 mmol) was added during 10 min.Small piece of ice (50 g) was added into the solution. The mixture wasadded at 0° C. to a suspension of 2,4-pentanedione (367 mg, 3.67 mmol)and potassium acetate (20 g) in ethanol (250 mL). The solution wasstirred for 15 min, and then was added to 250 mL of saturated Na₂CO₃aqueous solution, extracted with dichloromethane, washed with water andbrine, dried over Na₂SO₄, and concentrated under reduced pressure togive the title compound (870 mg, 96% yield) as a brown solid: ¹H NMR(400 MHz, CDCl₃): δ ppm 2.89 (3H, s), 2.93 (3H, s), 2.96 (3H, s), 3.16(3H, s), 7.77-7.83 (4H, m), 14.80 (1H, brs).

Reference Example 1843-{[4-(4-Methylpiperazin-1-yl)phenyl]hydrazono}pentane-2,4-dione

4-(4-Methylpiperazin-1-yl)aniline (1000 mg, 5.24 mmol) was added to asolution of 6 mL of phosphoric acid (85%) and 4 mL of nitric acid (65%)at −6° C. When the mixture reached to room temperature, it was cooled to−6° C. and sodium nitrite (361 mg, 5.24 mmol) was added during 10 min.Small piece of ice (50 g) was added into the solution. The mixture wasadded at 0° C. to a suspension of 2,4-pentanedione (524 mg, 5.24 mmol)and potassium acetate (30 g) in ethanol (400 mL). The solution wasstirred for 15 min, and then was added to 250 mL of saturated Na₂CO₃aqueous solution, extracted with dichloromethane, washed with water andbrine, dried over Na₂SO₄, and concentrated under reduced pressure togive the title compound (610 mg, 39% yield): ¹H NMR (400 MHz, CDCl₃): δppm 2.40 (3H, s), 2.50 (3H, s), 2.62 (3H, s), 3.10 (4H, t, J=5.2 Hz),3.25 (4H, t, J=4.8 Hz), 7.30 (2H, d, J=8.8 Hz), 7.37 (2H, d, J=7.6 Hz),15.08 (1H, brs).

Reference Example 1853-{[4-(1H-1,2,4-Triazol-1-yl)phenyl]hydrazono}pentane-2,4-dione

4-(1H-1,2,4-Triazol-1-yl)aniline (500 mg, 3.12 mmol) was added to asolution of 3 mL of phosphoric acid (85%) and 2 mL of nitric acid (65%)at −6° C. When the mixture reached to room temperature, it was cooled to−6° C. and sodium nitrite (216 mg, 3.12 mmol) was added during 10 min.Small piece of ice (50 g) was added into the solution. The mixture wasadded at 0° C. to a suspension of 2,4-pentanedione (312 mg, 3.12 mmol)and potassium acetate (20 g) in ethanol (250 mL). The solution wasstirred for 15 min, and then was added to 250 mL of saturated Na₂CO₃aqueous solution, extracted with dichloromethane, washed with water andbrine, dried over Na₂SO₄, and concentrated under reduced pressure togive the title compound (600 mg, 71% yield) as a brown solid: ¹H NMR(400 MHz, CDCl₃): δ ppm 2.54 (3H, s), 2.63 (3H, s), 7.55 (2H, d, J=8.8Hz), 7.74 (2H, d, J=8.8 Hz), 8.12 (1H, s), 8.54 (1H, s), 14.76 (1H, s).

Reference Example 1863-{[4-(Trifluoromethoxy)phenyl]diazenyl}pentane-2,4-dione3-{[4-(Trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

4-(Trifluoromethoxy)aniline (1.00 g, 6.9 mmol) was added to a solutionof 6 mL of phosphoric acid (85%) and 4 mL of nitric acid (65%) at −6°C., followed by sodium nitrite (0.601 g, 8.7 mmol, 1.2 equiv.) in 10 mLof water dropwise at 0° C., and the mixture was stirred at 0° C. for 30min. Then to the reaction mixture was added dropwise a mixture ofpotassium acetate (2.028 g, 20.7 mmol, 3.0 equiv.) and acetylacetone(0.8 mL, 7.0 mmol, 1.0 equiv.) in 20 mL of ethanol. The mixture wasstirred at room temperature for 15 min, filtered, extract with AcOEt,washed with brine and dried to give crude product (1.58 g, 88% yield),which was used directly to the next step. ¹H NMR (400 MHz, CDCl₃): δ ppm2.50 (s, 3H), 2.61 (s, 3H), 7.26-7.28 (m, 2H), 7.40-7.43 (m, 2H), 14.69(s, 1H).

Reference Example 1873-{[2-Fluoro-3-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione

To a solution of 2-fluoro-3-(trifluoromethyl)aniline (1.0 g, 5.58 mmol)in 8 mL of acetic acid and 1.3 mL of concentrated hydrochloridesolution, sodium nitrite (462 mg, 6.69 mmol) in 2.1 mL of water wasadded dropwise at 0° C., and the mixture was stirred at 0° C. for 1 h.Then to the reaction mixture were added sodium acetate (1.37 g, 16.8mmol) and acetylacetone (726 mg, 7.26 mmol). The mixture was stirred atroom temperature for 2 h, filtered, washed with water, EtOH/H₂O (1/1)and hexane, and dried to give the title compound (900 mg, 55% yield). ¹HNMR (400 MHz, CDCl₃): δ ppm 2.51 (s, 3H), 2.63 (s, 3H), 7.30-7.34 (m,1H), 7.38-7.41 (m, 1H), 7.94-7.96 (m, 1H), 14.66 (s, 1H).

Reference Example 188 3-[(2,3-Difluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 2,3-difluoroaniline (1.0 g, 7.75 mmol) in 11.1 mL ofacetic acid and 1.69 mL of concentrated hydrochloride solution, sodiumnitrite (600 mg, 9.3 mmol) in 2.7 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a mixture of sodium acetate (1.78 g, 21.7mmol, 3.0 equiv.) and acetylacetone (1 g, 10 mmol, 1.3 equiv.). Themixture was stirred at room temperature for 2 h, filtered, washed withwater, EtOH/H₂O (1/1) and hexane, and dried to give the title compound(900 mg, 48% yield): ¹H NMR (400 MHz, CDCl₃): δ ppm 2.49 (s, 3H), 2.61(s, 3H), 6.93-7.00 (m, 1H), 7.11-7.17 (m, 1H), 7.50-7.56 (m, 1H), 14.64(s, 1H).

Reference Example 1893-[(2,2-Difluoro-1,3-benzodioxol-4-yl)hydrazono]pentane-2,4-dione

A solution of sodium nitrite (0.96 g, 14 mmol) in H₂O (5 mL) was addeddropwise to a solution of 2,2-difluoro-1,3-benzodioxol-4-amine (2.0 g,12 mmol) in 6 M HCl aqueous solution (12 mL, 72 mmol) at 0° C. Afterstirring for 15 min at 0° C., the mixture was added to a suspension of2,4-pentanedione (1.2 mL, 12 mmol) and sodium acetate (5.9 g, 72 mmol)in MeOH (20 mL) pre-cooled at 0° C. The formed precipitate was collectedby filtration, washed with water and dissolved in AcOEt. The organicsolution was washed with saturated NaHCO₃ aqueous solution and brine,dried over MgSO₄, filtered and concentrated under reduced pressure togive the title compound (3.0 g, 90% yield) as orange crystals: ¹H NMR(300 MHz, CDCl₃): δ ppm 2.49 (3H, s), 2.63 (3H, s), 6.88 (1H, dd, J=8.0,1.1 Hz), 7.13 (1H, t, J=8.1 Hz), 7.30 (1H, dd, J=8.5, 1.1 Hz), 14.56(1H, brs).

Reference Example 1903-{[2-Fluoro-4-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione

To a solution of 2-fluoro-4-(trifluoromethyl)aniline (1.0 g, 5.58 mmol)in 8 mL of acetic acid and 1.3 mL of concentrated hydrochloridesolution, sodium nitrite (462 mg, 6.69 mmol) in 2.1 mL of water wasadded dropwise at 0° C., and the mixture was stirred at 0° C. for 1 h.Then to the reaction mixture were added sodium acetate (1.37 g, 16.8mmol, 3.0 equiv.) and acetylacetone (726 mg, 7.26 mmol, 1.3 equiv.) Themixture was stirred at room temperature for 2 h, filtered, washed withwater, EtOH/H₂O (1/1) and hexane, and dried to give the title compound(720 mg, yield 44%): ¹H NMR (400 MHz, CDCl₃): δ ppm 2.51 (s, 3H), 2.63(s, 3H), 7.42-7.50 (m, 2H), 7.86 (t, J=8.0 Hz, 1H), 14.56 (s, 1H).

Reference Example 191 tert-Butyl[4-(difluoromethoxy)-2-fluorophenyl]carbamate

A solution of 4-(difluoromethoxy)-2-fluorobenzoic acid (1 g, 4.85 mmol),DPPA (1.6 g, 5.83 mmol) and Et₃N (0.59 g, 5.83 mmol) in 16 mL of t-BuOHwas refluxed for 4 h, and then concentrated. The residue was dissolvedin dichloromethane (40 mL), washed with 1M HCl aqueous solution, driedover Na₂SO₄, and concentrated under reduced pressure. The crude productwas purified by flash column chromatography on silica gel(petroether/AcOEt=4/1) to get the title compound (850 mg, yield 63%) asa yellow solid: ¹H NMR (400 MHz, CDCl₃): δ ppm 1.53 (s, 9H), 6.44 (t,J=73.6 Hz, 1H), 6.89-6.92 (m, 1H), 7.24-7.27 (m, 1H), 7.37-7.41 (m, 1H).

Reference Example 1923-{[4-(Difluoromethoxy)-2-fluorophenyl]hydrazono}pentane-2,4-dione

A solution of tert-butyl [4-(difluoromethoxy)-2-fluorophenyl]carbamate(850 mg, 3.07 mmol) in 300 mL of HCl in AcOEt was stirred overnight andconcentrated under reduced pressure.

To a solution of the residue in 5.5 mL of acetic acid and 0.9 mL ofconcentrated hydrochloride solution, sodium nitrite (239 mg, 3.39 mmol)in 1.4 mL of water was added dropwise at 0° C., and the mixture wasstirred at 0° C. for 1 h. Then to the reaction mixture were added sodiumacetate (703 mg, 8.47 mmol, 3.0 equiv.) and acetylacetone (367 mg, 3.67mmol, 1.3 equiv.). The mixture was stirred at room temperature for 2 h,filtered, washed with water, EtOH/H₂O (1/1) and hexane, and dried togive the title compound (300 mg, 37% yield): ¹H NMR (400 MHz, CDCl₃): δppm 2.49 (s, 3H), 2.62 (s, 3H), 6.51 (t, J=72.8 Hz, 1H), 6.95-7.04 (m,2H), 7.73-7.77 (m, 1H), 14.70 (s, 1H).

Reference Example 193 2-Fluoro-4-(trifluoromethoxy)benzoic acid

A solution of 1-bromo-2-fluoro-4-(trifluoromethoxy)benzene (8 g, 30.8mmol) in 170 mL of THF was cooled to −40° C., and then i-PrMgBr (0.4mol/L in THF, 91 mL) was injected. After being stirred for 3 h, CO₂ wasinjected for 2 h at 0° C. The mixture was washed with 1M HCl aqueoussolution, separated. The aqueous layer was extracted with CH₂Cl₂. Thecombined organic layers were dried over Na₂SO₄, and concentrated underreduced pressure. The residue was washed with petroether to give thetitle compound (6 g, 87% yield): ¹H NMR (400 MHz, CDCl₃): δ ppm7.05-7.12 (m, 2H), 8.10 (t, J=8.4 Hz, 1H).

Reference Example 194 tert-Butyl[2-fluoro4-(trifluoromethoxy)phenyl]carbamate

A solution of 2-fluoro-4-(trifluoromethoxy)benzoic acid (3 g, 13.4mmol), DPPA (4.4 g, 16.1 mmol) and Et₃N (1.63 g, 16.1 mmol) in 130 mL oft-BuOH was refluxed for 4 h, and then concentrated. The residue wasdissolved in dichloromethane (200 mL), washed with 1M HCl aqueoussolution, dried over Na₂SO₄, and concentrated under reduced pressure.The crude product was purified by flash column chromatography on silicagel (petroether/AcOEt=4/1) to get the title compound (2 g, 50% yield) asa yellow solid: ¹H NMR (400 MHz, CDCl₃): δ ppm 1.27 (s, 9H), 6.97-7.03(m, 1H), 7.21-7.27 (m, 1H), 7.37-7.41 (m, 1H).

Reference Example 1953-{[2-Fluoro-4-(trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione

A solution of tert-butyl [2-fluoro4-(trifluoromethoxy)phenyl]carbamate(2 g, 6.8 mmol) in 300 mL of HCl in AcOEt was stirred for 3 h at 0° C.and concentrated under reduced pressure.

To a solution of the residue in 20 mL of acetic acid and 3.5 mL ofconcentrated hydrochloride solution, sodium nitrite (507 mg, 7.34 mmol)in 5 mL of water was added dropwise at 0° C., and the mixture wasstirred at 0° C. for 1 h. Then to the reaction mixture were added sodiumacetate (1.5 g, 18.3 mmol, 3.0 equiv.) and acetylacetone (793 mg, 7.93mmol, 1.3 equiv.). The mixture was stirred at room temperature for 2 h,filtered, washed with water, EtOH/H₂O (1/1) and hexane, and dried togive the title compound (920 mg, 50% yield): ¹H NMR (400 MHz, CDCl₃): δppm 2.50 (s, 3H), 2.63 (s, 3H), 7.08-7.13 (m, 2H), 7.78 (t, J=8.8 Hz,1H), 14.65 (s, 1H).

Reference Example 196 3-[(2,4-Difluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 2,4-difluoroaniline (1.0 g, 7.75 mmol) in 11.1 mL ofacetic acid and 1.69 mL of concentrated hydrochloride solution, sodiumnitrite (600 mg, 9.3 mmol) in 2.7 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture was added dropwise a mixture of sodium acetate (1.78 g, 21.7mmol) and acetylacetone (1 g, 10 mmol). The mixture was stirred at roomtemperature for 2 h, filtered, washed with water, EtOH/H₂O (1/1) andhexane, and dried to give the title compound (550 mg, 30% yield): ¹H NMR(400 MHz, CDCl₃): δ ppm 2.48 (s, 3H), 2.61 (s, 3H), 6.91-7.00 (m, 2H),7.70-7.76 (m, 1H), 14.72 (s, 1H).

Reference Example 1973-[(4-Chloro-2-fluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 4-chloro-2-fluoroaniline (1 g, 6.87 mmol) in 9.8 mL ofacetic acid and 1.6 mL of concentrated hydrochloride solution, sodiumnitrite (568 mg, 8.24 mmol) in 2.6 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture were added sodium acetate (1.69 g, 20.6 mmol) and acetylacetone(893 mg, 8.93 mmol). The mixture was stirred at room temperature for 2h, filtered, washed with water, EtOH/H₂O (1/1) and hexane, and dried togive the title compound (1 g, 57% yield): ¹H NMR (400 MHz, CDCl₃): δ ppm2.49 (s, 3H), 2.60 (s, 3H), 7.15-7.25 (m, 2H), 7.69 (t, J=8.4 Hz, 1H),14.64 (s, 1H).

Reference Example 1983-{[2-Fluoro-5-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione

2-Fluoro-5-(trifluoromethyl)aniline (2.00 g, 15.6 mmol) was added to asolution of 15.6 mL of HOAc and 2.6 mL of concentrated HCl, stirred,followed by sodium nitrite (0.925 g, 13.4 mmol) in 4 mL of waterdropwise at 0° C., and the mixture was stirred at 0° C. for 60 min. Thenpotassium acetate (3.28 g, 3.5 mmol) and acetylacetone (1.83 mL, 14.5mmol) were added dropwise. The mixture was stirred at room temperatureovernight, filtered. The precipitate was dissolved in CH₂Cl₂, washedwith water, dried over Na₂SO₄ and concentrated under reduced pressure togive the title compound (2.06 g, 64% yield): ¹H NMR (400 MHz, CDCl₃): δppm 2.53 (s, 3H), 2.64 (s, 3H), 7.26-6.30 (m, 1H), 7.39-7.42 (m, 1H),7.99-8.01 (m, 1H), 14.62 (s, 1H).

Reference Example 199 3-[(2,5-Difluorophenyl)hydrazono]pentane-2,4-dione

2,5-Difluoroaniline (2.10 g, 15.5 mmol) was added to a solution of 21.6mL of HOAc and 3.6 mL of concentrated HCl, stirred, followed by sodiumnitrite (1.28 g, 18.6 mmol) in 6 mL of water dropwise at 0° C., and themixture was stirred at 0° C. for 60 min. Then potassium acetate (4.56 g,46.5 mmol) and acetylacetone (2.07 mL, 20.15 mmol) were added dropwise.The mixture was stirred at room temperature overnight, filtered. Theprecipitate was dissolved in CH₂Cl₂, washed with water, dried overNa₂SO₄ and concentrated under reduced pressure to give a crude product(4.00 g, 67% yield), which was used directly to the next step: ¹H NMR(400 MHz, CDCl₃): δ ppm 2.51 (s, 3H), 2.62 (s, 3H), 6.79-6.83 (m, 1H),7.09-7.15 (m, 1H), 7.43-7.47 (m, 1H), 14.57 (s, 1H)

Reference Example 200 3-[(2,6-Difluorophenyl)hydrazono]pentane-2,4-dione

To a solution of 2,6-difluoroaniline (1.0 g, 7.75 mmol) in 11.1 mL ofacetic acid and 1.69 mL of concentrated hydrochloride solution, sodiumnitrite (600 mg, 9.3 mmol) in 2.7 mL of water was added dropwise at 0°C., and the mixture was stirred at 0° C. for 1 h. Then to the reactionmixture were added sodium acetate (1.78 g, 21.7 mmol) and acetylacetone(1 g, 10 mmol). The mixture was stirred at room temperature for 2 h,filtered, washed with water, EtOH/H₂O (1:1) and hexane, and dried togive the title compound (400 mg, 21% yield): ¹H NMR (400 MHz, CDCl₃): δppm 2.43 (s, 3H), 2.61 (s, 3H), 6.97-7.03 (m, 2H), 7.05-7.15 (m, 1H),14.42 (s, 1H).

Reference Example 2013-(1H-Pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(2.70 g, 8 mmol) and NH₂NH₂.H₂O (1.94 mL, 40 mmol) in MeOH (25 mL) wasrefluxed overnight. After cooling to room temperature, the reactionmixture was poured into 1 M HCl aqueous solution and extracted withAcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with AcOEt and recrystallizedfrom AcOEt to give the title compound (0.969 g, 40% yield) as anoff-white solid: mp 192-194° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 6.82(1H, d, J=7.9 Hz), 7.03 (1H, d, J=1.9 Hz), 7.69 (1H, d, J=1.9 Hz),7.72-7.76 (2H, m), 7.83-7.89 (1H, m), 7.91-7.93 (1H, m), 8.33 (1H, d,J=7.9 Hz), 12.85 (1H, brs). LC-MS (ESI) m/z 307 [M+H]⁺. Anal. Calcd forC₁₄H₉F₃N₄O: C, 54.91; H, 2.96; N, 18.29. Found: C, 54.92; H, 2.99; N,18.33.

Reference Example 2023-[(4-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione

4-Morpholin-4-ylaniline (653 mg, 3.67 mmol) was added to a mixture of 3mL of phosphoric acid (85%) and 2 mL of nitric acid (65%) at −6° C. Whenthe resulting mixture reached to room temperature, it was cooled to −6°C. and sodium nitrite (253 mg, 3.67 mmol) was added during 10 min. Smallpiece of ice (50 g) was added into the solution. The mixture was addedat 0° C. to a suspension of 2,4-pentanedione (367 mg, 3.67 mmol) andpotassium acetate (20 g) in ethanol (250 mL). The solution was stirredfor 15 min, and then added to 250 mL of saturated Na₂CO₃ aqueoussolution, extracted with dichloromethane, washed with water and brine,dried over anhydrous Na₂SO₄, and concentrated under reduced pressure togive the title compound (870 mg, 82% yield) as a brown solid: ¹H NMR(400 MHz, CDCl₃): δ 2.50 (3H, s), 2.61 (3H, s), 3.15-3.18 (4H, m),3.80-3.83 (4H, m), 6.98-7.03 (2H, m), 7.45-7.50 (2H, m), 14.37 (1H, s).

Reference Example 2033-[3-(Dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

3-[(4-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione (500 mg, 1.73mmol) was dissolved in 10 mL of N,N-Dimethylformamide dimethyl acetal.The mixture was refluxed for 4 h and concentrated under reduced pressureto give the title compound as a brown oil which was used to the nextstep without further purification: ¹H NMR (400 MHz, CDCl₃): δ 2.85-2.90(3H, m), 3.10-3.14 (3H, m), 3.18-3.21 (4H, m), 3.85-3.88 (4H, m),5.63-5.66 (1H, m), 6.68 (1H, d, J=8.0 Hz), 6.94-6.96 (2H, m), 7.45-7.48(2H, m), 7.72 (1H, brs), 8.12 (1H, d, J=8.0 Hz).

Reference Example 2043-Acetyl-1-(2-fluoro-5-iodophenyl)-5-methoxypyridazin-4(1H)-one

To a mixture of1-(2-fluoro-5-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(4.33 g, 10.0 mmol) in THF (1.0 L) was added MeMgBr (1.0 M in THF, 20.0mL, 20.0 mmol) at −78° C. under N₂. The mixture was stirred at −78° C.for 2 h. The reaction was quenched with saturated NH₄Cl aqueous solutionat −78° C. The mixture was diluted with saturated NaHCO₃ aqueoussolution, extracted with EtOAc, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on silica gel(hexane/EtOAc=50/50 to 0/100 and EtOAc/MeOH=100/0 to 0/100) andtriturated with EtOAc/hexane to yield the title compound (3.58 g, 92%yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 2.50(3H, s), 3.80 (3H, s), 7.38 (1H, dd, J=11.0, 8.7 Hz), 7.95 (1H, ddd,J=8.7, 4.5, 2.3 Hz), 8.15 (1H, dd, J=7.2, 2.3 Hz), 8.52 (1H, d, J=1.5Hz).

Reference Example 205 1-[2-Fluoro-4-(1H-pyrazol-1-yl)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A suspension of1-(2-fluoro-4-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(1.73 g, 4 mmol), pyrazole (0.408 g, 6 mmol), Cu₂O (0.057 g, 0.4 mmol),salicylaldoxime (0.219 g, 1.6 mmol), and Cs₂CO₃ (2.60 g, 8 mmol) inCH₃CN (8 mL) was refluxed for 6 h under Ar atmosphere. After cooling toroom temperature, the reaction mixture was poured into water andextracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby basic silica gel column chromatography eluting with AcOEt andrecrystallized from MeOH/H₂O to give the title compound (0.370 g, 25%yield) as a white solid: mp 187-189° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.40 (3H, s), 3.72 (3H, s), 3.93 (3H, s), 6.55 (1H, dd, J=1.5, 2.3 Hz),7.60 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.71-7.77 (3H, m), 7.84 (1H, d,J=2.3 Hz), 7.98 (1H, d, J=2.6 Hz). Anal. Calcd for C₁₇H₁₆FN₅O₄: C,54.69; H, 4.32; N, 18.76. Found: C, 54.58; H, 4.40; N, 18.67.

Reference Example 2063-Acetyl-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 2.8 mL, 2.8 mmol) was added dropwise at−78° C. to a solution of1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(351 mg, 0.94 mmol) in THF (100 mL). After stirring for 1 h, thereaction mixture was quenched with 1 M HCl aqueous solution andextracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby silica gel column chromatography eluting with AcOEt andrecrystallized from MeOH/H₂O to give the title compound (223 mg, 72%yield) as a pale yellow solid: mp 159-161° C.; ¹H NMR (300 MHz, CDCl₃):δ ppm 2.69 (3H, s), 3.93 (3H, s), 6.56 (1H, dd, J=1.5, 2.3 Hz), 7.64(1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.71-7.79 (4H, m), 7.99 (1H, d, J=2.6Hz). Anal. Calcd for C₁₆H₁₃FN₄O₃: C, 58.54; H, 3.99; N, 17.07. Found: C,58.42; H, 4.01; N, 16.98.

Reference Example 207 Methyl4-methoxy-3-oxo-2-(pyridin-3-ylhydrazono)butanoate

A solution of 3-aminopyridine (20 g, 210 mmol) in 6 M HCl aqueoussolution (200 ml, 1200 mmol) was cooled with ice bath. To the solutionwas added dropwise a solution of sodium nitrite (18 g, 260 mmol) inwater (40 mL). After stirring at 0° C. for 5 min, the mixture was addedto a mixture of sodium acetate (130 g, 1300 mmol) and methyl4-methoxyacetoacetate (28 ml, 210 mmol) in EtOH (300 ml) and water (150ml) at 0° C., and the mixture was stirred at 0° C. for 1 h. The mixturewas diluted with water (150 ml), extracted with AcOEt (500 ml×3). Thecombined organic layer was washed with saturated NaHCO₃ aqueous solution(300 ml×3) and brine (300 ml), dried over Na₂SO₄, filtered andconcentrated under reduced pressure to give the title compound (52 g,97% yield) as a brown oil: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.50 (3H×1/2,s), 3.51 (3H×1/2, s), 3.89 (3H×1/2, s), 3.93 (3H×1/2, s), 4.67 (2H×1/2,s), 4.70 (2H×1/2, s), 7.35-7.43 (1H, m), 7.67-7.74 (1H×1/2, m),7.84-7.91 (1H×1/2, m), 8.41-8.49 (1H, m), 8.64-8.71 (1H, m), 12.90(1H×1/2, s), 14.76 (1H×1/2, brs).

Reference Example 208 Methyl5-methoxy-4-oxo-1-pyridin-3-yl-1,4-dihydropyridazine-3-carboxylate

A mixture of methyl 4-methoxy-3-oxo-2-(pyridin-3-ylhydrazono)butanoate(52 g, 210 mmol) in N,N-dimethylformamide dimethyl acetal (80 mL, 600mmol) was refluxed for 30 min. The mixture was allowed to cool to roomtemperature and stayed at room temperature overnight. The formedcrystals were collected by filtration and washed with AcOEt to give thetitle compound (35 g, 64% yield) as pale yellow crystals: ¹H NMR (300MHz, CDCl₃): δ ppm 3.98 (3H, s), 3.98 (3H, s), 7.48-7.54 (1H, m), 7.96(1H, s), 8.04 (1H, ddd, J=8.4, 2.6, 1.5 Hz), 8.71 (1H, dd, J=4.9, 1.5Hz), 8.93 (1H, d, J=2.6 Hz).

Reference Example 2095-Methoxy-4-oxo-1-pyridin-3-yl-1,4-dihydropyridazine-3-carboxylic acidhydrochloride

A solution of methyl5-methoxy-4-oxo-1-pyridin-3-yl-1,4-dihydropyridazine-3-carboxylate (2.0g, 7.7 mmol) in 6 M HCl aqueous solution (20 ml) was refluxed for 4 h.The mixture was concentrated under reduced pressure to give the titlecompound (2.1 g, 95% yield) as off-white crystals: ¹H NMR (300 MHz,DMSO-d₆): δ ppm 3.98 (3H, s), 7.78 (1H, dd, J=8.7, 4.5 Hz), 8.36-8.42(1H, m), 8.79 (1H, dd, J=4.5, 1.1 Hz), 9.02 (1H, s), 9.15 (1H, d, J=2.6Hz).

Reference Example 210N,5-Dimethoxy-N-methyl-4-oxo-1-pyridin-3-yl-1,4-dihydropyridazine-3-carboxamide

A mixture of5-methoxy-4-oxo-1-pyridin-3-yl-1,4-dihydropyridazine-3-carboxylic acidhydrochloride (1.0 g, 3.5 mmol), N,O-dimethylhydroxylamine hydrochloride(0.52 g, 5.3 mmol), TEA (1.5 ml, 11 mmol) andO-benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium tetrafluoroborate (1.2g, 3.9 mmol) in DMF (15 ml) was stirred at room temperature overnight.The mixture was diluted with AcOEt. The precipitate was filtered off andthe filtrate was concentrated under reduced pressure. The residue waschromatographed on basic silica gel (0/100-20/80 MeOH/AcOEt) to give thetitle compound (0.81 g, 79% yield) as white crystals: ¹H NMR (300 MHz,CDCl₃): δ ppm 3.41 (3H, s), 3.71 (3H, s), 3.98 (3H, s), 7.48 (1H, dd,J=8.3, 4.5 Hz), 7.97 (1H, s), 8.00-8.05 (1H, m), 8.67 (1H, dd, J=4.5,1.3 Hz), 8.91 (1H, d, J=2.6 Hz).

Reference Example 2113-Acetyl-5-methoxy-1-pyridin-3-ylpyridazin-4(1H)-one

To a solution ofN,5-dimethoxy-N-methyl-4-oxo-1-pyridin-3-yl-1,4-dihydropyridazine-3-carboxamide(0.40 g, 1.4 mmol) in THF (10 ml) was added dropwise 1 M MeMgBr in THF(3.0 ml, 3.0 mmol) at −78° C. After stirring at −78° C. for 2 h, themixture was quenched with water (0.5 ml) and stirred at room temperaturefor 1 h. The mixture was concentrated under reduced pressure. Theresidue was partitioned between CHCl₃ (25 ml) and brine. The aqueouslayer was extracted with CHCl₃ (25 ml×3). The combined organic layer wasdried over Na₂SO₄, filtered and concentrated under reduced pressure togive the title compound (0.21 g, 62% yield) as yellow crystals: ¹H NMR(300 MHz, CDCl₃): δ ppm 2.70 (3H, s), 3.97 (3H, s), 7.49-7.56 (1H, m),7.95 (1H, s), 8.01-8.08 (1H, m), 8.72 (1H, dd, J=4.7, 1.3 Hz), 8.95 (1H,d, J=2.6 Hz).

Reference Example 212 Methyl2-[(4-bromo-2,5-difluorophenyl)hydrazono]-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (7.9 g, 115 mmol) in H₂O (20 mL) was added dropwiseat 0° C. to a mixture of 4-bromo-2,5-difluoroaniline (20 g, 96 mmol) and6 M HCl aqueous solution (96 mL, 576 mmol). After stirring for 15 min,the resulting aqueous solution was added to a suspension of methyl4-methoxyacetoacetate (12.4 mL, 96 mmol) and NaOAc (34 g, 576 mmol) inMeOH (165 mL) pre-cooled at 0° C. The precipitate was collected byfiltration, washed with water and dried at room temperature to give thetitle compound (37 g, 100% yield) as a red solid: ¹H NMR (300 MHz,DMSO-d₆): δ ppm 3.34 (3H, s), 3.83 (3H, s), 4.68 (2H, s), 7.70 (1H, dd,J=9.7, 7.0 Hz), 7.89 (1H, dd, J=10.6, 6.1 Hz), 12.16 (1H, s).

Reference Example 213 Methyl 1-(4-bromo-2,5-difluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-[(4-bromo-2,5-difluorophenyl)hydrazono]-4-methoxy-3-oxobutanoate (33g, 90 mmol) in N,N-dimethylformamide dimethyl acetal (72 mL) was stirredat 110° C. for 3 h. After cooling to room temperature, the mixture wasconcentrated under reduce pressure. To the residue were added MeOH andsilica gel The mixture was evaporated and purified by silica gel columnchromatography eluting with hexane/AcOEt (1/0 to 0/1) and thenAcOEt/MeOH (4/1) to give the title compound (27.9 g, 83% yield) as abrown gum: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.80 (3H, s), 3.83 (3H, s),8.01 (1H, dd, J=8.7, 6.8 Hz), 8.15 (1H, dd, J=9.8, 6.0 Hz), 8.55 (1H, d,J=1.5 Hz). LC-MS (ESI) m/z 376 [M+H]⁺.

Reference Example 214 1-(4-Bromo-2,5-difluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

A solution of methyl1-(4-bromo-2,5-difluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(25 g, 68 mmol) and 2 M NaOH aqueous solution (68 mL) in EtOH (68 mL)was stirred at room temperature overnight. The solvent was removed byevaporation and resulting aqueous solution was acidified by 6 M HClaqueous solution (12 mL). The precipitate was collected by filtrationand azeotroped with toluene to give the title compound (25 g, 100%yield) as a brown solid: LC-MS (ESI) m/z 376 [M+H]⁺.

Reference Example 215 1-(4-Bromo-2, 5-difluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(4-bromo-2,5-difluorophenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (25 g, 83 mmol), N,O-dimethylhydroxylamine hydrochloride (8.9 g, 91mmol), HOBt (12 g, 91 mmol), triethylamine (24 mL, 174 mmol) and WSC (17g, 91 mmol) in DMF (160 mL) was stirred at room temperature for 18 h.The mixture was diluted with AcOEt, washed with water and brine, driedover MgSO₄ and concentrated under reduced pressure. The residue waspurified by silica gel column chromatography eluting with Hexane/AcOEt(1/0 to 0/1) and then AcOEt/MeOH (10/1) to give the title compound (11g, 31% yield) as a yellow solid: LC-MS (ESI) m/z 405 [M+H]⁺.

Reference Example 2163-Acetyl-1-(4-bromo-2,5-difluorophenyl)-5-methoxypyridazin-4(1H)-one

A solution of1-(4-bromo-2,5-difluorophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(5.0 g, 12 mmol) in THF (100 mL) was added dropwise to MeMgBr (1.0 M inTHF, 50 mL, 50 mmol) at −78° C. under N₂. The mixture was stirred at−78° C. for 1 h. The reaction was quenched with 1 M HCl aqueous solution(70 mL) at −78° C. The mixture warmed up to room temperature andextracted with AcOEt. The organic layer was dried over MgSO₄ andconcentrated under reduced pressure to give the title compound (3.6 g,80% yield) as a yellow solid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 2.50 (3H,s), 3.80 (3H, s), 8.03 (1H, dd, J=8.9, 6.6 Hz), 8.17 (1H, dd, J=10.0,6.2 Hz), 8.52 (1H, d, J=1.5 Hz). LC-MS (ESI) m/z 360 [M+H]⁺.

Reference Example 217 5,5-Dimethyl-1,3-oxazolidin-2-one

The mixture of 1-amino-2-methylpropanol (1.03 g, 11.6 mmol) and CDI(1.87 g, 11.6 mmol) in THF (40 ml) was stirred at room temperature for15 h. After solvent evaporated, the residue was purified by silica gelcolumn chromatography (AcOEt/hexane=25%-100%) to give the title compound(1.13 g, 85% yield) as a colorless solid: ¹H NMR (300 MHz, CDCl₃): δ ppm1.48 (6H, s), 3.35 (2H, s), 5.86 (1H, brs)

Reference Example 218 4-Oxa-6-azaspiro[2.4]heptan-5-one

A solution of 1-(aminomethyl)cyclopropanol (0.58 g, 6.7 mmol) and CDI(1.1 g, 6.7 mmol) in THF (20 ml) was stirred at room temperatureovernight. The mixture was concentrated under reduced pressure. Theresidue was chromatographed on silica gel (25/75-70/30 AcOEt/hexane) togive the title compound (0.42 g, 56% yield) as white crystals: ¹H NMR(300 MHz, CDCl₃): δ ppm 0.68-0.75 (2H, m), 1.20-1.27 (2H, m), 3.68 (2H,s), 5.48 (1H, brs).

Reference Example 2191-(4-Iodo-2-methoxyphenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A solution of NaNO₂ (24.8 g, 360 mmol) in H₂O (75 mL) was added dropwiseat 0° C. to a mixture of 2-fluoro-4-iodoaniline (71.1 g, 300 mmol) and 6M HCl aqueous solution (300 mL). After stirring for 15 min, theresulting aqueous solution was added to a suspension of methyl4-methoxyacetoacetate (43.8 g, 300 mmol) and NaOAc (147.6 g, 1.8 mol) inMeOH (600 mL) pre-cooled at 0° C. The precipitate was collected byfiltration, washed with water, dried in air overnight. A solution of theproduct in N,N-dimethylformamide dimethyl acetal (450 mL) was refluxedfor 4 h. After cooling to room temperature, the precipitate wascollected by filtration and rinsed with hexane/AcOEt (1/1). Theresulting products (54 g) were used the next reaction without furtherpurification.

To a suspension of the products (54 g) in THF/MeOH (1/1, 400 mL) wasadded 10% NaOH aqueous solution (200 mL) at 0° C. The mixture wasstirred at room temperature for 45 min. To the suspension was added 10%HCl aqueous solution (200 mL) at 0° C. The mixture was stirred at roomtemperature for 1 h. The precipitates were collected by filtration andrinsed with ^(i)Pr₂O. The resulting products (45 g) were used the nextreaction without further purification.

A mixture of the products (45 g), N-methoxymethanamine hydrochloride(12.4 g, 127 mmol), HOBt (18.7 g, 138 mmol), WSC (26.5 g, 138 mmol) andEt₃N (48.2 mL, 346 mmol) in DMF (500 mL) was stirred at room temperatureovernight. The mixture was partitioned between AcOEt and H₂O, and theorganic layer was washed with NaCl aqueous solution, dried over Na₂SO₄and evaporated. The residue was purified by column chromatography onsilica gel (AcOEt/MeOH=100/0 to 95/5) to yield the title compound (32.7g, 20% yield) as a white solid and1-(2-fluoro-4-iodophenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(10 g, 6% yield) as a white solid. ¹H NMR (300 MHz, CDCl₃): δ ppm 3.38(3H, s), 3.70 (3H, s), 3.88 (3H, s), 3.89 (3H, s), 7.23 (1H, d, J=8.3Hz), 7.37 (1H, d, J=1.9 Hz), 7.43 (1H, dd, J=8.3, 1.9 Hz), 7.77 (1H, s).LC-MS (ESI) m/z 446 [M+H]⁺.

Reference Example 220N,5-Dimethoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A suspension of1-(4-iodo-2-methoxyphenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(10.7 g, 24 mmol), pyrazole (1.63 g, 24 mmol), Cu₂O (0.343 g, 2.4 mmol),salicylaldoxime (1.32 g, 9.6 mmol), and Cs₂CO₃ (15.6 g, 48 mmol) inCH₃CN (100 mL) was refluxed for 4 h under Ar atmosphere. After coolingto room temperature, the reaction mixture was poured into water andextracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby basic silica gel column chromatography eluting with AcOEt/THF(1/0-0/1) to give the title compound (6.32 g, 68% yield) as a paleyellow amorphous solid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.39 (3H, s),3.73 (3H, s), 3.91 (3H, s), 3.99 (3H, s), 6.53 (1H, dd, J=1.9, 2.3 Hz),7.27 (1H, dd, J=2.3, 8.7 Hz), 7.58 (1H, d, J=8.7 Hz), 7.61 (1H, d, J=1.9Hz), 7.77 (1H, d, J=1.5 Hz), 7.84 (1H, s), 7.98 (1H, d, J=2.3 Hz).

Reference Example 2213-Acetyl-5-methoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]pyridazin-4(1H)-one

MeMgBr (1 M solution in THF, 50 mL, 50 mmol) was added dropwise at −78°C. to a solution ofN,5-dimethoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(6.32 g, 16.4 mmol) in THF (100 mL). After stirring for 1 h, thereaction mixture was quenched with 1 M HCl aqueous solution andextracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was washedwith AcOEt and recrystallized from MeOH to give the title compound (1.53g, 27% yield) as pale yellow prisms: mp 193-196° C.; ¹H NMR (300 MHz,CDCl₃): δ ppm 2.69 (3H, s), 3.90 (3H, s), 4.00 (3H, s), 6.54 (1H, dd,J=1.9, 2.3 Hz), 7.30 (1H, dd, J=2.3, 8.7 Hz), 7.57 (1H, d, J=8.7 Hz),7.63 (1H, d, J=2.3 Hz), 7.77-7.78 (2H, m), 8.00 (1H, d, J=2.3 Hz). Anal.Calcd for C₁₇H₁₆N₄O₄: C, 59.99; H, 4.74; N, 16.46. Found: C, 59.68; H,5.00; N, 16.26.

Reference Example 222 4-(2,3-Difluoro-4-nitrophenyl)morpholine

A mixture of 1,2,3-trifluoro-4-nitrobenzene (4.0 mL, 35 mmol),morpholine (3.1 mL, 35 mmol), and K₂CO₃ (4.8 g, 35 mmol) in DMSO (35 mL)was stirred at room temperature overnight. The mixture was diluted withAcOEt and washed with water and brine. The organic layer was dried overMgSO₄, and concentrated under reduced pressure. The residue wasrecrystallized from AcOEt to give the title compound (11.5 g, 67% yield)as a pale yellow solid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.09-3.51 (4H,m), 3.58-4.08 (4H, m), 6.98 (1H, ddd, J=9.8, 8.1, 2.1 Hz), 7.94 (1H,ddd, J=9.9, 8.0, 2.1 Hz). LC-MS (ESI) m/z 245 [M+H]⁺.

Reference Example 223 2,3-Difluoro-4-morpholin-4-ylaniline

A mixture of 4-(2,3-difluoro-4-nitrophenyl)morpholine (11.5 g, 47 mmol)and 10% Pd—C (50% wet, 1.2 g) in EtOH (150 mL) was hydrogenated for 5 hat room temperature. The reaction mixture was filtered by celite and thefiltrate was concentrated under reduced pressure. The residue wasrecrystallized from ^(i)Pr₂O/AcOEt to give the title compound (8.7 g,86% yield) as a pale red powder: ¹H NMR (300 MHz, DMSO-d₆): δ ppm2.77-2.95 (4H, m), 3.60-3.79 (4H, m), 5.07 (2H, s), 6.49 (1H, td, J=9.0,1.9 Hz), 6.62 (1H, td, J=8.9, 2.3 Hz). LC-MS (ESI) m/z 215 [M+H]⁺.

Reference Example 224 Methyl2-[(2,3-difluoro-4-morpholin-4-ylphenyl)hydrazono]-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (3.4 g, 49 mmol) in H₂O (10 mL) was added dropwiseat 0° C. to a mixture of 2,3-difluoro-4-morpholin-4-ylaniline (8.7 g, 41mmol) and 6 M HCl aqueous solution (41 mL, 244 mmol). After stirring for15 min, the resulting aqueous solution was added to a suspension ofmethyl 4-methoxyacetoacetate (5.2 mL, 41 mmol) and NaOAc (14.3 g, 244mmol) in MeOH (40 mL) pre-cooled at 0° C. The mixture was adjusted to pH7 with 1 M NaOH aqueous solution (200 mL). The precipitate was collectedby filtration, washed with water and dried at room temperature to givethe title compound (4.7 g, 31% yield) as a red solid: LC-MS (ESI) m/z372 [M+H]⁺.

Reference Example 225 Methyl1-(2,3-difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-[(2,3-difluoro-4-morpholin-4-ylphenyl)hydrazono]-4-methoxy-3-oxobutanoate(4.7 g, 13 mmol) in N,N-dimethylformamide dimethyl acetal (20 mL) wasstirred at 100° C. for 80 min. After cooling to room temperature, theprecipitate was collected by filtration and washed with ^(i)Pr₂O to givethe title compound (4.1 g, 84% yield) as a brown powder: ¹H NMR (300MHz, DMSO-d₆): δ ppm 3.13 (4H, dt, J=4.4, 2.5 Hz), 3.49-4.05 (10H, m),7.03 (1H, td, J=8.8, 2.5 Hz), 7.51 (1H, td, J=8.5, 2.3 Hz), 8.53 (1H, d,J=1.5 Hz). LC-MS (ESI) m/z 382 [M+H]⁺.

Reference Example 2261-(2,3-Difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

A solution of methyl1-(2,3-difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(4.1 g, 11 mmol) and 2 M NaOH aqueous solution (11 mL, 22 mmol) in EtOH(20 mL) was stirred at room temperature for 16 h. To the mixture wasadded 1 M HCl aqueous solution (21 mL). The precipitate was collected byfiltration and dried over under reduced pressure to give the titlecompound (3.8 g, 98% yield) as a white solid: ¹H NMR (300 MHz, DMSO-d₆):δ ppm 3.06-3.23 (4H, m), 3.66-3.82 (4H, m), 3.88 (3H, s), 6.84-7.27 (1H,m), 7.36-7.74 (1H, m), 8.86 (1H, d, J=1.1 Hz), 14.95 (1H, brs). LC-MS(ESI) m/z 368 [M+H]⁺.

Reference Example 227 1-(2,3-Difluoro-4-morpholin-4-ylphenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(2,3-difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (3.8 g, 10 mmol), N,O-dimethylhydroxylamine hydrochloride (1.1 g,11 mmol), HOBt (1.5 g, 11 mmol), triethylamine (2.9 mL, 21 mmol) and WSC(2.2 g, 11 mmol) in DMF (20 mL) was stirred at room temperatureovernight. The mixture was diluted with AcOEt, washed with water andbrine, dried over MgSO₄ and concentrated under reduced pressure to givethe title compound (3.3 g, 77% yield) as a brown solid: ¹H NMR (300 MHz,DMSO-d₆): δ ppm 3.05-3.18 (4H, m), 3.24 (3H, s), 3.57 (3H, s), 3.68-4.02(7H, m), 7.03 (1H, td, J=8.8, 2.1 Hz), 7.27-7.81 (1H, m), 8.50 (1H, s).LC-MS (ESI) m/z 411 [M+H]⁺.

Reference Example 2283-Acetyl-1-(2,3-difluoro-4-morpholin-4-ylphenyl)-5-methoxypyridazin-4(1H)-one

A solution of1-(2,3-difluoro-4-morpholin-4-ylphenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(1.1 g, 2.6 mmol) in THF (25 mL) was added dropwise to MeMgBr (1.0 M inTHF, 11 mL, 11 mmol) at −78° C. under N₂. The mixture was stirred at−78° C. for 1 h. The reaction was quenched with 1 M HCl aqueous solution(11 mL) at −78° C. The mixture warmed up to room temperature, dilutedwith AcOEt, and washed with brine. The organic layer was dried overMgSO₄, and concentrated under reduced pressure. The residue wasrecrystallized from ^(i)Pr₂O/AcOEt to give the title compound (870 mg,92% yield) as a pale yellow solid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 2.49(3H, s), 2.90-3.28 (4H, m), 3.64-4.01 (7H, m), 7.05 (1H, td, J=8.9, 2.3Hz), 7.53 (1H, td, J=8.6, 2.5 Hz), 8.50 (1H, d, J=1.9 Hz). LC-MS (ESI)m/z 366 [M+H]⁺.

Reference Example 229 4-(2, 5-Difluoro-4-nitrophenyl)morpholine

A mixture of 1,2,4-trifluoro-5-nitrobenzene (4.0 mL, 35 mmol),morpholine (3.1 mL, 35 mmol), and K₂CO₃ (4.8 g, 35 mmol) in DMSO (35 mL)was stirred at room temperature overnight. The mixture was diluted withAcOEt and washed with water and brine. The organic layer was dried overMgSO₄, and concentrated under reduced pressure. The residue wasrecrystallized from AcOEt to give the title compound (10 g, 63% yield)as a pale yellow solid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.15-3.49 (4H,m), 3.50-3.90 (4H, m), 7.13 (1H, dd, J=14.3, 7.5 Hz), 8.01 (1H, dd,J=13.6, 7.5 Hz). LC-MS (ESI) m/z 245 [M+H]⁺.

Reference Example 230 2,5-Difluoro-4-morpholin-4-ylaniline

A mixture of 4-(2,5-difluoro-4-nitrophenyl)morpholine (11 g, 44 mmol)and 10% Pd—C (50% wet, 1.1 g) in EtOH (150 mL) was hydrogenated for 5 hat room temperature. The reaction mixture was filtered by celite, andthe filtrate was concentrated under reduced pressure. The residue wasrecrystallized from ^(i)Pr₂O/AcOEt to give the title compound (8.6 g,91% yield) as a pale red powder: ¹H NMR (300 MHz, DMSO-d₆): δ ppm2.66-2.95 (4H, m), 3.56-3.83 (4H, m), 5.00 (2H, s), 6.55 (1H, dd,J=13.8, 8.5 Hz), 6.77 (1H, dd, J=12.8, 8.3 Hz). LC-MS (ESI) m/z 215[M+H]⁺.

Reference Example 231 Methyl 2-[(2,5-difluoro-4-morpholin-4-ylphenyl)hydrazono]-4-methoxy-3-oxobutanoate

A solution of NaNO₂ (3.3 g, 48 mmol) in H₂O (10 mL) was added dropwiseat 0° C. to a mixture of 2,5-difluoro-4-morpholin-4-ylaniline (8.6 g, 40mmol) and 6 M HCl aqueous solution (40 mL, 240 mmol). After stirring for15 min, the resulting aqueous solution was added to a suspension ofmethyl 4-methoxyacetoacetate (5.2 mL, 40 mmol) and NaOAc (14 g, 240mmol) in MeOH (40 mL) pre-cooled at 0° C. The mixture was adjusted to pH7 with 1 M NaOH aqueous solution (200 mL). The precipitate was collectedby filtration, washed with water and dried at room temperature to givethe title compound (9.51 g, 64% yield) as a red solid: LC-MS (ESI) m/z372 [M+H]⁺.

Reference Example 232 Methyl1-(2,5-difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate

A solution of methyl2-[(2,5-difluoro-4-morpholin-4-ylphenyl)hydrazono]-4-methoxy-3-oxobutanoate(2.8 g, 7.5 mmol) in N,N-dimethylformamide dimethyl acetal (18 mL) wasstirred at 100° C. for 80 min. After cooling to room temperature, theprecipitate was collected by filtration and washed with ^(i)Pr₂O to givethe title compound (2.7 g, 95% yield) as a brown powder: ¹H NMR (300MHz, DMSO-d₆): δ ppm 3.12 (4H, dt, J=4.4, 2.5 Hz), 3.48-4.31 (10H, m),7.18 (1H, dd, J=12.5, 7.6 Hz), 7.72 (1H, dd, J=12.5, 7.2 Hz), 8.50 (1H,s). LC-MS (ESI) m/z 382 [M+H]⁺.

Reference Example 2331-(2,5-Difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid

A solution of methyl1-(2,5-difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylate(2.7 g, 7.1 mmol) and 2 M NaOH aqueous solution (7.2 mL, 14.4 mmol) inEtOH (14 mL) was stirred at room temperature for 16 h. To the mixturewas added 1 M HCl aqueous solution (14 mL). The precipitate wascollected by filtration and dried over under reduced pressure to givethe title compound (2.5 g, 96% yield) as a white solid: ¹H NMR (300 MHz,DMSO-d₆): δ ppm 3.00-3.24 (4H, m), 3.67-3.82 (4H, m), 3.88 (3H, s), 7.23(1H, dd, J=12.7, 7.7 Hz), 7.74 (1H, dd, J=12.8, 7.2 Hz), 8.83 (1H, d,J=1.1 Hz), 14.95 (1H, brs). LC-MS (ESI) m/z 368 [M+H]⁺.

Reference Example 234 1-(2,5-Difluoro-4-morpholin-4-ylphenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide

A mixture of1-(2,5-difluoro-4-morpholin-4-ylphenyl)-5-methoxy-4-oxo-1,4-dihydropyridazine-3-carboxylicacid (2.5 g, 6.8 mmol), N,O-dimethylhydroxylamine hydrochloride (0.73 g,7.5 mmol), HOBt (1.0 g, 7.5 mmol), triethylamine (2.0 mL, 14 mmol) andWSC (1.4 g, 7.5 mmol) in DMF (28 mL) was stirred at room temperatureovernight. The mixture was diluted with AcOEt, washed with water andbrine, dried over MgSO₄ and concentrated under reduced pressure to givethe title compound (1.6 g, 58% yield) as a brown solid: ¹H NMR (300 MHz,DMSO-d₆): δ ppm 3.01-3.19 (4H, m), 3.24 (3H, s), 3.56 (3H, s), 3.62-3.91(7H, m), 7.17 (1H, dd, J=12.7, 7.7 Hz), 7.62-7.82 (1H, m), 8.48 (1H, s).LC-MS (ESI) m/z 411 [M+H]⁺.

Reference Example 2353-Acetyl-1-(2,5-difluoro-4-morpholin-4-ylphenyl)-5-methoxypyridazin-4(1H)-one

A solution of1-(2,5-difluoro-4-morpholin-4-ylphenyl)-N,5-dimethoxy-N-methyl-4-oxo-1,4-dihydropyridazine-3-carboxamide(0.51 g, 1.2 mmol) in THF (40 mL) was added dropwise to MeMgBr (1.0 M inTHF, 5.0 mL, 5.0 mmol) at −78° C. under N₂. The mixture was stirred at−78° C. for 2 h. The reaction was quenched with 1 M HCl aqueous solution(5.0 mL) at −78° C. The mixture warmed up to room temperature, dilutedwith AcOEt, and washed with brine. The organic layer was dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby silica gel column chromatography eluting with AcOEt/MeOH (10/0 to10/1) to give the title compound (340 mg, 75% yield) as a pale yellowsolid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 2.49 (3H, s), 2.91-3.21 (4H, m),3.54-3.89 (7H, m), 7.19 (1H, dd, J=12.7, 7.7 Hz), 7.74 (1H, dd, J=12.8,7.2 Hz), 8.46 (1H, d, J=1.5 Hz). LC-MS (ESI) m/z 366 [M+H]⁺.

Example 13-[1-(4-Methylphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added4-methylphenylhydrazine hydrochloride (237 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(4-methylphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale yellow solid (108 mg, 27%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 2.33 (s, 3H), 6.68 (d, J=8 Hz, 1H),7.20 (d, J=1.6 Hz, 1H), 7.29-7.23 (m, 4H), 7.46 (d, J=8 Hz, 1H), 7.50(s, 1H), 7.62 (t, J=8 Hz, 1H), 7.72 (d, J=8 Hz, 1H), 7.81 (d, J=1.6 Hz,1H), 8.95 (d, J=8 Hz, 1H). LC-MS (MH⁺⁾397.15.; mp 164-165° C.

Example 23-[1-(4-Fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added4-fluorophenylhydrazine hydrochloride (244 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(4-fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale brown solid (119 mg, 30%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 6.68 (d, J=8 Hz, 1H), 7.29-7.24 (m,3H), 7.50-7.45 (m, 3H), 7.62 (d, J=8 Hz, 1H), 7.68 (d, J=8 Hz, 1H), 7.74(d, J=8 Hz, 1H), 7.84 (d, J=1.6 Hz, 1H), 8.95 (d, J=8 Hz, 1H). LC-MS(MH⁺) 401.14.; mp 130-131° C.

Example 33-[1-(4-Chlorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added4-chlorophenylhydrazine hydrochloride (269 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(4-chlorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale brown solid (126 mg, 30%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 6.69 (d, J=8 Hz, 1H), 7.25 (d, J=1.2Hz, 1H), 7.51-7.47 (m, 4H), 7.57 (m, 2H), 7.68 (t, J=8 Hz, 1H), 7.75 (d,J=8 Hz, 1H), 7.86 (d, J=1.2 Hz, 1H), 8.98 (d, J=8 Hz, 1H). LC-MS (MH⁺)417.08.; mp 166-167° C.

Example 43-[1-(4-Methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added4-methoxyphenylhydrazine hydrochloride (262 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(4-methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale yellow solid (154 mg, 37%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 3.76 (s, 3H), 6.67 (d, J=8 Hz, 1H),6.98 (d, J=8 Hz, 2H), 7.20 (d, J=1.6 Hz, 1H), 7.32 (d, J=8 Hz, 2H), 7.50(d, J=8 Hz, 1H), 7.55 (s, 1H), 7.62 (t, J=8 Hz, 1H), 7.73 (d, J=8 Hz,1H), 7.79 (d, J=1.6 Hz, 1H), 8.95 (d, J=8 Hz, 1H). LC-MS (MH⁺) 413.16.;mp 173-174° C.

Example 53-[1-(3-Methylphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added3-methylphenylhydrazine hydrochloride (237 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(3-methylphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale yellow solid (84 mg, 21%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 2.31 (s, 3H), 6.68 (d, J=8 Hz, 1H),7.12 (d, J=8 Hz, 1H), 7.21 (d, J=8 Hz, 1H), 7.23 (d, J=1.6 Hz, 1H),7.32-7.28 (m, 2H), 7.43 (d, J=8 Hz, 1H), 7.49 (s, 1H), 7.62 (t, J=8 Hz,1H), 7.72 (d, J=8 Hz, 1H), 7.82 (d, J=1.6 Hz, 1H), 8.94 (d, J=8 Hz, 1H).LC-MS (MH⁺) 397.18.; mp 142-143° C.

Example 63-[1-(3-Fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(674 mg, 2.0 mmol) in ethanol (200 mL) were added3-fluorophenylhydrazine hydrochloride (488 mg, 3.0 mmol) and Et₃N (0.56mL, 4.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(3-fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale yellow solid (201 mg, 25%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 6.69 (d, J=8 Hz, 1H), 7.24-7.20 (m,2H), 7.26 (d, J=2.0 Hz, 1H), 7.40 (d, J=2.0 Hz, 1H), 7.46 (q, J=2.0 Hz,1H), 7.54 (s, 1H), 7.61 (d, J=8 Hz, 1H), 7.67 (d, J=8 Hz, 1H), 7.74 (d,J=8 Hz, 1H), 7.87 (d, J=2.0 Hz, 1H), 8.97 (d, J=8 Hz, 1H). LC-MS (MH⁺)401.14.; mp 104-105° C.

Example 73-[1-(2-Methylphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added2-methylphenylhydrazine hydrochloride (237 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(2-methylphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale pink solid (85 mg, 21%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 1.92 (s, 3H), 6.68 (d, J=8 Hz, 1H),7.05 (d, J=8 Hz, 1H), 7.23 (d, J=8 Hz, 1H), 7.31-7.28 (m, 1H), 7.38-7.35(m, 2H), 7.42 (d, J=2.0 Hz, 1H), 7.56 (t, J=8 Hz, 2H), 7.70 (d, J=8 Hz,1H), 7.84 (d, J=2.0 Hz, 1H), 8.88 (d, J=8 Hz, 1H). LC-MS (MH⁺) 397.11.;mp 126-127° C.

Example 83-[1-(2-Chlorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(674 mg, 2.0 mmol) in ethanol (200 mL) were added2-chlorophenylhydrazine hydrochloride (538 mg, 3.0 mmol) and Et₃N (0.56mL, 4.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(2-chlorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale yellow solid (280 mg, 34%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 6.70 (d, J=8 Hz, 1H), 7.12 (d, J=8 Hz,1H), 7.61-7.48 (m, 7H), 7.71 (d, J=8 Hz, 1H), 7.88 (d, J=1.6 Hz, 1H),8.90 (d, J=8 Hz, 1H). LC-MS (MH⁺) 417.08.; mp 139-140° C.

Example 93-[1-(2-Methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) were added2-methoxyphenylhydrazine hydrochloride (262 mg, 1.5 mmol) and Et₃N (0.28mL, 2.0 mmol). The mixture was stirred at 100° C. for 3 h and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-[1-(2-methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a pale yellow solid (78 mg, 19%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 3.46 (s, 3H), 6.69 (d, J=8 Hz, 1H),7.03 (d, J=8 Hz, 1H), 7.14 (t, J=8 Hz, 2H), 7.25 (d, J=2.0 Hz, 1H), 7.41(t, J=8 Hz, 2H), 7.50 (d, J=8 Hz, 1H), 7.58 (t, J=8 Hz, 1H), 7.68 (d,J=8 Hz, 1H), 7.79 (d, J=1.6 Hz, 1H), 8.90 (d, J=8 Hz, 1H). LC-MS (MH⁺)413.16.; mp 146-147° C.

Example 103-(1-Phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(337 mg, 1.0 mmol) in ethanol (100 mL) was added phenylhydrazine (163mg, 1.5 mmol). The mixture was stirred at 100° C. for 3 h, and thesolvent was removed under reduced pressure. Preparative HPLCchromatography provided3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas a gray solid (55 mg, 15%).

¹H NMR (400 MHz, DMSO-d₆): δ ppm 6.68 (d, J=8 Hz, 1H), 7.23 (d, J=1.6Hz, 1H), 7.48-7.39 (m, 6H), 7.51 (s, 1H), 7.61 (t, J=8 Hz, 1H), 7.71 (d,J=8 Hz, 1H), 7.84 (d, J=1.6 Hz, 1H), 8.95 (d, J=8 Hz, 1H). LC-MS (MH⁺)383.15.; mp 156-157° C.

Example 113-(1-Phenyl-1H-pyrazol-5-yl)-1-[4-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[4-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(crude 718 mg, 2.13 mmol) in 20 mL of methanol was added phenylhydrazine(345 mg, 3.20 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give3-(1-phenyl-1H-pyrazol-5-yl)-1-[4-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(100 mg, 12% for two steps) as a yellow solid.

¹H NMR (300 MHz, CDCl₃): δ ppm 6.74 (d, J=7.6 Hz, 1H), 6.90 (d, J=8.4Hz, 2H), 7.39-7.41 (m, 1H), 7.42 (d, J=2.0 Hz, 1H), 7.44-7.50 (m, 4H),7.53 (d, J=8.4 Hz, 2H), 7.81 (d, J=1.6 Hz, 1H), 8.21 (d, J=8.0 Hz, 1H);LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.422 min; MS Calcd.: 382, MS Found: 383 (M⁺+H).; mp237-238° C.

Example 121-(3-Chlorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-(3-chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude 573 mg, 1.89 mmol) in 20 mL of methanol was added phenylhydrazine(306 mg, 2.84 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(3-chlorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (125mg, 19% for two steps) as a yellow solid.

¹H NMR (300 MHz, DMSO-d₆): δ ppm 6.71-6.74 (m, 2H), 6.80-6.83 (m, 1H),7.22-7.25 (m, 2H), 7.39-7.49 (m, 6H), 7.81 (d, J=1.6 Hz, 1H), 8.15 (d,J=8.0 Hz, 1H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5%water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=3.150 min; MS Calcd.: 348, MS Found: 349(M⁺+H).; mp 146-147° C.

Example 131-(2-Methoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(2-methoxyphenyl)pyridazin-4(1H)-one(crude 639 mg, 2.14 mmol) in 20 mL of methanol was added phenylhydrazine(347 mg, 3.21 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(2-methoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (35mg, 5% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 3.82 (s, 3H), 6.37 (dd, J=10.4, 2.4 Hz,1H), 6.60 (d, J=10.0 Hz, 1H), 6.78-6.83 (m, 1H), 6.96 (dd, J=11.2, 1.6Hz, 1H), 7.25 (d, J=2.4 Hz, 1H), 7.21-7.41 (m, 6H), 7.76 (d, J=2.8 Hz,1H), 8.01 (d, J=10.4 Hz, 1H); LCMS (mobile phase: from 70% water and 30%CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under these conditionsfor 0.5 min.) purity is >95%, Rt=2.589 min; MS Calcd.: 344, MS Found:345 (M⁺+H).; mp 153-154° C.

Example 141-(4-Methoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-methoxyphenyl)pyridazin-4(1H)-one(crude 640 mg, 2.14 mmol) in 20 mL of methanol was added phenylhydrazine(347 mg, 3.21 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(4-methoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (127mg, 17% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 3.81 (s, 3H), 6.67-6.76 (m, 5H),7.38-7.44 (m, 6H), 7.78 (d, J=2.8 Hz, 1H), 8.08 (d, J=10.4 Hz, 1H); LCMS(mobile phase: from 70% water and 30% CH₃CN to 5% water and 95% CH₃CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=2.639 min; MS Calcd.: 344, MS Found: 345 (M⁺+H).; mp 179-180° C.

Example 151-(3-Fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(3-fluorophenyl)pyridazin-4(1H)-one(crude, 840 mg, 2.93 mmol) in 20 mL of methanol was addedphenylhydrazine (474 mg, 4.39 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(3-fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (169mg, 17% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.36-6.41 (m, 1H), 6.68-6.75 (m, 2H),6.95-7.01 (m, 1H), 7.24-7.32 (m, 1H), 7.38-7.49 (m, 6H), 7.79 (d, J=2.4Hz, 1H), 8.15 (d, J=10.4 Hz, 1H); LCMS (mobile phase: from 70% water and30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under theseconditions for 0.5 min.) purity is >95%, Rt=2.834 min; MS Calcd.: 332,MS Found: 333 (M⁺+H).; mp 170-171° C.

Example 161-(2-Fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(2-fluorophenyl)pyridazin-4(1H)-one(crude 776 mg, 2.70 mmol) in 20 mL of methanol was added phenylhydrazine(438 mg, 4.10 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(2-fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (278mg, 31% for two steps) as a yellow solid.

¹H NMR (300 MHz, CDCl₃): δ ppm 6.39-6.46 (m, 1H), 6.65 (d, J=7.8 Hz,1H), 6.97-7.03 (m, 1H), 7.13-7.20 (m, 1H), 7.27-7.46 (m, 7H), 7.78 (d,J=1.8 Hz, 1H), 8.02 (dd, J=7.8, 2.4 Hz, 1H); LCMS (mobile phase: from70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finallyunder these conditions for 0.5 min.) purity is >95%, Rt=2.634 min; MSCalcd.: 332, MS Found: 333 (M⁺+H).; mp 124-125° C.

Example 171-(4-Fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-fluorophenyl)pyridazin-4(1H)-one(crude 840 mg, 2.93 mmol) in 20 mL of methanol was added phenylhydrazine(474 mg, 4.39 mmol) The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(4-fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (260mg, 27% for two steps) as a brown solid.

¹H NMR (300 MHz, DMSO-d₆): δ ppm 6.62 (d, J=7.8 Hz, 1H), 7.11-7.15 (m,2H), 7.20-7.26 (m, 3H), 7.37-7.40 (m, 2H), 7.44-7.49 (m, 3H), 7.81 (d,J=1.8 Hz, 1H), 8.78 (d, J=8.1 Hz, 1H); LCMS (mobile phase: from 70%water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally underthese conditions for 0.5 min.) purity is >95%, Rt=2.779 min; MS Calcd.:332, MS Found: 333 (M⁺+H).; mp 252-253° C.

Example 181-(4-Chlorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-(4-chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude, 764 mg, 2.52 mmol) in 20 mL of methanol was addedphenylhydrazine (408 mg, 3.78 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(4-chlorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (70mg, 8% for two steps) as a brown solid.

¹H NMR (300 MHz, CDCl₃): δ ppm 6.68-6.73 (m, 3H), 7.24 (dd, J=6.9, 2.4Hz, 2H), 7.38-7.46 (m, 6H), 7.78 (d, J=1.8 Hz, 1H), 8.12 (d, J=7.8 Hz,1H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% water and95% CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.180 min; MS Calcd.: 348, MS Found: 349 (M⁺+H).; mp219-220° C.

Example 191-(2-Methylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(2-methylphenyl)pyridazin-4(1H)-one(crude, 1298 mg, 4.59 mmol) in 20 mL of methanol was addedphenylhydrazine (744 mg, 6.89 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(2-methylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (180mg, 12% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 2.01 (s, 3H), 6.67 (d, J=8.0 Hz, 1H),6.84 (d, J=7.6 Hz, 1H), 7.15-7.25 (m, 2H), 7.29-7.38 (m, 7H), 7.79-7.83(m, 2H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% waterand 95% CH₃CN in 6 min, finally under these conditions for 0.5 min.)purity is >95%, Rt=2.679 min; MS Calcd.: 328, MS Found: 329 (M⁺+H).; mp120-121° C.

Example 201-(3-Methylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(3-methylphenyl)pyridazin-4(1H)-one(crude, 650 mg, 2.29 mmol) in 20 mL of methanol was addedphenylhydrazine (370 mg, 3.44 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(3-methylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (55mg, 7% for two steps) as a brown solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 2.32 (s, 3H), 6.60 (s, 1H), 6.72-6.74 (m,2H), 7.12 (d, J=7.6 Hz, 1H), 7.21 (t, J=8.0 Hz, 1H), 7.41-7.50 (m, 6H),7.81 (s, 1H), 8.19 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from 70% waterand 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under theseconditions for 0.5 min.) purity is >95%, Rt=2.972 min; MS Calcd.: 328,MS Found: 329 (M⁺+H).; mp 115-116° C.

Example 211-(3-Methoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(3-methoxyphenyl)pyridazin-4(1H)-one(crude 640 mg, 2.14 mmol) in 20 mL of methanol was added phenylhydrazine(347 mg, 3.21 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(3-methoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (106mg, 14% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 3.76 (s, 3H), 6.46 (dd, J=8.0, 1.6 Hz,1H), 6.51 (t, J=2.0 Hz, 1H), 6.71 (d, J=8.0 Hz, 1H), 6.84 (dd, J=8.4,2.0 Hz, 1H), 7.21 (t, J=8.4 Hz, 1H), 7.35-7.43 (m, 6H), 7.81 (d, J=2.0Hz, 1H), 8.17 (d, J=8.4 Hz, 1H); LCMS (mobile phase: from 70% water and30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under theseconditions for 0.5 min.) purity is >95%, Rt=2.753 min; MS Calcd.: 344,MS Found: 345 (M⁺+H).; mp 110-111° C.

Example 223-(1-Phenyl-1H-pyrazol-5-yl)-1-[2-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[2-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(crude 785 mg, 2.33 mmol) in 20 mL of methanol was added phenylhydrazine(377 mg, 3.50 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give3-(1-phenyl-1H-pyrazol-5-yl)-1-[2-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(105 mg, 12% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.59 (d, J=7.6 Hz, 1H), 6.97-7.00 (m,1H), 7.14 (d, J=2.0 Hz, 1H), 7.27-7.35 (m, 5H), 7.57-7.60 (m, 2H),7.75-7.81 (m, 3H); LCMS (mobile phase: from 70% water and 30% CH₃CN to5% water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=2.896 min; MS Calcd.: 382, MS Found: 383(M⁺+H).; mp 145-146° C.

Example 231-(4-Morpholin-4-ylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one(crude, 1100 mg, 3.11 mmol) in 20 mL of methanol was addedphenylhydrazine (504 mg, 4.67 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(4-morpholin-4-ylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(95 mg, 8% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 3.19 (t, J=4.8 Hz, 4H), 3.89 (t, J=4.8Hz, 4H), 6.71-6.79 (m, 5H), 7.40-7.48 (m, 6H), 7.82 (s, 1H), 8.11 (d,J=7.6 Hz, 1H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5%water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=2.391 min; MS Calcd.: 399, MS Found: 400(M⁺+H).; mp 205-206° C.

Example 24 1-Phenyl-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-phenylpyridazin-4(1H)-one (crude 620mg, 2.30 mmol) in 20 mL of methanol was added phenylhydrazine (996 mg,9.22 mmol). The mixture was refluxed for 4 h and concentrated. Theresidue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-phenyl-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (50 mg, yield7% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.71 (d, J=8.0 Hz, 1H), 6.81-6.84 (m,2H), 7.29-7.30 (m, 3H), 7.40-7.47 (m, 6H), 7.79 (d, J=2.0 Hz, 1H), 8.17(d, J=8.0 Hz, 1H); LCMS (mobile phase: from 90% water and 10% CH₃CN to5% water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=3.548 min; MS Calcd.: 314, MS Found: 315(M+H).; mp 179-180° C.

Example 251-(4-Methylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-methylphenyl)pyridazin-4(1H)-one(crude, 600 mg, 2.12 mmol) in 20 mL of methanol was addedphenylhydrazine (916 mg, 8.48 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(4-methylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (50mg, 7% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 2.34 (s, 3H), 6.69 (d, J=7.6 Hz, 3H),7.08 (d, J=8.4 Hz, 2H), 7.40-7.47 (m, 6H), 7.79 (d, J=2.0 Hz, 1H), 8.13(d, J=8.0 Hz, 1H); LCMS (mobile phase: from 90% water and 10% CH₃CN to5% water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=3.789 min; MS Calcd.: 328, MS Found: 329(M⁺+H).; mp 182-183° C.

Example 261-[2-(Difluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-[2-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude 622 mg, 1.85 mmol) in 20 mL of methanol was added phenylhydrazine(800 mg, 7.40 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-[2-(difluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(30 mg, 4% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.38 (t, J=72.0 Hz, 1H), 6.57-6.60 (m,1H), 6.63 (d, J=8.0 Hz, 1H), 7.13 (dd, J=8.0, 0.8 Hz, 1H), 7.23-7.26 (m,2H), 7.36-7.40 (m, 6H), 7.78 (d, J=1.6 Hz, 1H), 7.96 (d, J=8.0 Hz, 1H);LCMS (mobile phase: from 80% water and 20% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.317 min; MS Calcd.: 380, MS Found: 381 (M⁺+H).; mp123-124° C.

Example 271-[3-(Difluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-[3-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude, 993 mg, 2.96 mmol) in 20 mL of methanol was addedphenylhydrazine (480 mg, 4.44 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-[3-(difluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(160 mg, 14% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.31 (s, 0.25*1H), 6.49 (s, 0.5*1H), 6.62(t, J=2.4 Hz, 1H), 6.68 (s, 0.25*1H), 6.74 (d, J=7.6 Hz, 1H), 6.79 (dq,J=8.0, 0.8 Hz, 1H), 7.09 (dd, J=8.4, 1.2 Hz, 1H), 7.33 (t, J=8.0 Hz,1H), 7.72-7.48 (m, 6H), 7.83 (d, J=2.0 Hz, 1H), 8.19 (d, J=8.0 Hz, 1H);LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.027 min; MS Calcd.: 380, MS Found: 381 (M⁺+H).; mp159-160° C.

Example 281-[4-(Difluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-[4-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude 747 mg, 2.22 mmol) in 20 mL of methanol was added phenylhydrazine(360 mg, 3.33 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-[4-(difluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(190 mg, 22% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.35 (s, 0.25*1H), 6.54 (s, 0.5*1H), 6.72(s, 0.25*1H), 6.73 (d, J=8.0 Hz, 1H), 6.82 (dd, J=6.8, 2.0 Hz, 2H), 7.07(d, J=9.2 Hz, 2H), 7.42-7.51 (m, 6H), 7.82 (d, J=2.0 Hz, 1H), 8.14 (d,J=8.0 Hz, 1H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5%water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=3.007 min; MS Calcd.: 380, MS Found: 381(M⁺+H).; mp 175-176° C.

Example 291-(2-Morpholin-4-ylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(2-morpholin-4-ylphenyl)pyridazin-4(1H)-one(crude, 870 mg, 2.46 mmol) 20 mL of methanol was added phenylhydrazine(400 mg, 3.69 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-(2-morpholin-4-ylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(50 mg, 5% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 2.73 (t, J=4.4 Hz, 4H), 3.70 (t, J=4.4Hz, 4H), 6.45 (dd, J=8.0, 1.6 Hz, 1H), 6.68 (d, J=8.0 Hz, 1H), 6.95-6.99(m, 1H), 7.07 (dd, J=8.0, 1.2 Hz, 1H), 7.28-7.29 (m, 1H), 7.32-7.41 (m,6H), 7.81 (d, J=2.4 Hz, 1H), 8.27 (d, J=7.6 Hz, 1H); LCMS (mobile phase:from 70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finallyunder these conditions for 0.5 min.) purity is >95%, Rt=2.641 min; MSCalcd.: 399, MS Found: 400 (M⁺+H).; mp 200-201° C.

Example 303-(1-Phenyl-1H-pyrazol-5-yl)-1-pyridin-3-ylpyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-pyridin-3-ylpyridazin-4(1H)-one(crude 260 mg, 0.98 mmol) in 20 mL of methanol was added phenylhydrazine(423 mg, 3.92 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give3-(1-phenyl-1H-pyrazol-5-yl)-1-pyridin-3-ylpyridazin-4(1H)-one (60 mg,19% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.75 (d, J=7.2 Hz, 1H), 7.00-7.03 (m,1H), 7.22-7.26 (m, 1H), 7.39-7.50 (m, 6H), 7.82 (d, J=2.0 Hz, 1H), 8.18(d, J=7.6 Hz, 1H), 8.26 (d, J=2.4 Hz, 1H), 8.55 (dd, J=4.8, 1.2 Hz, 1H);LCMS (mobile phase: from 90% water and 10% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=2.872 min; MS Calcd.: 315, MS Found: 316 (M⁺+H).; mp176-177° C.

Example 313-(1-Phenyl-1H-pyrazol-5-yl)-1-pyridin-4-ylpyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-pyridin-4-ylpyridazin-4(1H)-one(crude 158 mg, 0.58 mmol) in 20 mL of methanol was added phenylhydrazine(253 mg, 2.34 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give3-(1-phenyl-1H-pyrazol-5-yl)-1-pyridin-4-ylpyridazin-4(1H)-one (30 mg,16% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.72-6.75 (m, 3H), 7.31-7.52 (m, 6H),7.82 (d, J=1.6 Hz, 1H), 8.27 (d, J=8.0 Hz, 1H), 8.50-8.52 (m, 2H); LCMS(mobile phase: from 90% water and 10% CH₃CN to 5% water and 95% CH₃CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=2.850 min; MS Calcd.: 315, MS Found: 316 (M⁺+H).; mp 202-203° C.

Example 321-(2-Chlorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-(2-chlorophenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude, 636 mg, 2.10 mmol) in 20 mL of methanol was addedphenylhydrazine (907 mg, 8.40 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(2-chlorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one (60mg, 8% for two steps) as a red gel.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.63 (d, J=8.0 Hz, 1H), 6.67 (dd, J=8.0,1.6 Hz, 1H), 7.18-7.22 (m, 2H), 7.27-7.40 (m, 6H), 7.44-7.46 (m, 1H),7.76 (d, J=1.6 Hz, 1H), 7.91 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finallyunder these conditions for 0.5 min.) purity is >95%, Rt=2.662 min; MSCalcd.: 348, MS Found: 349 (M⁺+H).; mp 138-139° C.

Example 333-[1-(1-Methylethyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(500 mg, 1.5 mmol) in ethanol (10 mL) were added isopropylhydrazinehydrochloride (246 mg, 2.2 mmol) and Et₃N (0.41 mL, 3.0 mmol). Themixture was stirred at 100° C. for 5 h. The mixture was diluted with 1NHCl aqueous solution, extracted with AcOEt, washed with brine, driedover Na₂SO₄, concentrated in vacuo, purified by column chromatography onsilica gel (hexane/AcOEt=10/90 to 0/100) and recrystallized withAcOEt/i-Pr₂O to yield the title compound as a pale yellow solid (323 mg,63%).

¹H NMR (300 MHz, DMSO-d₆) δ ppm 1.43 (d, J=6.4 Hz, 6H), 4.84-5.07 (m,1H), 6.70 (d, J=8.0 Hz, 1H), 6.92 (d, J=1.9 Hz, 1H), 7.58 (d, J=1.5 Hz,1H), 7.83 (d, J=5.3 Hz, 2H), 8.04-8.13 (m, 1H), 8.14 (s, 1H), 9.00 (d,J=8.0 Hz, 1H). LC-MS (M⁺) 348.55.; mp 183-184° C.

Example 343-[1-(2-Methylpropyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(500 mg, 1.5 mmol) in ethanol (10 mL) were added 2-methylpropylhydrazinehydrochloride (274 mg, 2.2 mmol) and Et₃N (0.41 mL, 3.0 mmol). Themixture was stirred at 100° C. for 5 h. The mixture was diluted with 1NHCl aqueous solution, extracted with AcOEt, washed with brine, driedover Na₂SO₄, concentrated in vacuo, purified by column chromatography onsilica gel (hexane/AcOEt=10/90 to 0/100) and recrystallized withAcOEt/i-Pr₂O to yield the title compound as a pale yellow solid (289 mg,54%).

¹H NMR (300 MHz, DMSO-d₆) δ ppm 0.73 (d, J=6.8 Hz, 6H), 2.12 (dt,J=13.6, 6.8 Hz, 1H), 4.22 (d, J=7.6 Hz, 2H), 6.70 (d, J=8.0 Hz, 1H),7.14 (d, J=1.9 Hz, 1H), 7.55 (d, J=1.9 Hz, 1H), 7.74-7.93 (m, 2H),7.98-8.26 (m, 2H), 8.95 (d, J=7.6 Hz, 1H). LC-MS (M⁺) 362.77.; mp120-121° C.

Example 353-(1-Pyridin-2-yl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(800 mg, 2.4 mmol) in ethanol (20 mL) were added 2-hydrazinepyridine(388 mg, 3.6 mmol) and Et₃N (0.66 mL, 4.7 mmol). The mixture was stirredat 100° C. for 5 h. The mixture was diluted with water, extracted withAcOEt, washed with brine, dried over Na₂SO₄, concentrated in vacuo,purified by HPLC and recrystallized with AcOEt/hexane to yield the titlecompound as a pale yellow solid (460 mg, 51%).

¹H NMR (300 MHz, DMSO-d₆) δ ppm 6.57 (d, J=7.9 Hz, 1H), 6.97 (s, 1H),7.18-7.42 (m, 1H), 7.60-8.10 (m, 7H), 8.21 (d, J=4.5 Hz, 1H), 8.99 (d,J=8.3 Hz, 1H). LC-MS (M⁺) 383.82.; mp 189-190° C.

Preparative HPLC was performed at the conditions described below.

Column: Sepax HP-C18 (30×50 mm S-10 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=90/10)→1.20 min (A/B=90/10)→4.75 min(A/B=0/100)→7.80 min (A/B=0/100)→7.90 min (A/B=90/10)→9.00 min(A/B=90/10)

Flow rate: 70 mL/min

Detector: UV 220 nm

Concentration: 80 mg/mL

Inject volume: 1250 μL

Example 361-[3-(Methylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one(0.727 g, 2.02 mmol) in acetic acid (25 mL, 80% in water) was treatedwith potassium permanganate (0.500 g, 3.16 mmol) and the resultingmixture was stirred at ambient temperature for 2 h. After this time, thereaction was directly concentrated to remove acetic acid and neutralizedwith saturated sodium bicarbonate to pH=7. After extraction with ethylacetate (3×100 mL), the combined organic layers were dried overmagnesium sulfate, filtered and concentrated. Flash chromatography(silica, methylene chloride to 94:6 methylene chloride:methanol),followed by crystallization from methanol and two subsequent preparativeHPLC purifications gave1-[3-(methylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(0.062 g, 8%) as a white solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 3.26 (s, 3H), 6.67 (d, J=7.9 Hz, 1H),7.18 (d, J=1.9 Hz, 1H), 7.26-7.29 (m, 1H), 7.39-7.42 (m, 3H), 7.44-7.48(m, 2H), 7.63 (t, J=8.0 Hz, 1H), 7.83 (d, J=1.9 Hz, 1H), 7.87-7.90 (m,1H), 8.01 (t, J=2.0 Hz, 1H), 8.96 (d, J=7.9 Hz, 1H); APCI MS m/z 393[M+H]⁺; mp 199-200° C.

Example 371-[3-(1H-Benzimidazol-2-yloxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(3-hydroxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(0.113 g, 0.342 mmol) and 2-chlorobenzimidazole (0.075 g, 0.49 mmol) inEt₃N (1 mL) was sealed and stirred at 120° C. for 14 h and then at 160°C. for 64 h. After this time, the reaction was diluted with ethylacetate (50 mL), washed with saturated sodium bicarbonate aqueoussolution (40 mL), and then with 2 N sodium hydroxide (3×20 mL). Theorganic layer was washed with brine, dried over magnesium sulfate,filtered and concentrated. Flash chromatography (silica, methylenechloride to 1:19 methanol/methylene chloride) afforded1-[3-(1H-benzimidazol-2-yloxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(33 mg, 18%) as a light-yellow solid.

¹H NMR (500 MHz, DMSO-d₆) δ 6.65 (d, J=7.9 Hz, 1H), 6.90 (s, 1H),7.12-7.19 (m, 4H), 7.25-7.34 (m, 5H), 7.37-7.46 (m, 3H), 7.47 (t, J=8.2Hz, 1H), 7.81 (d, J=1.8 Hz, 1H), 8.87 (d, J=8.0 Hz, 1H), 12.43 (s, 1H);APCI MS m/z 447 [M+H]⁺; mp 149-150° C.

Example 381-[3-(Methylsulfinyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(methylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one(0.180 g, 0.50 mmol), sodium bicarbonate (0.168 g, 2.0 mmol) inmethylene chloride (8 mL) was treated with 3-chloroperoxybenzoic acid(0.140 g, 77%, 0.62 mmol) and the resulting mixture was stirred atambient temperature for 2 h. After this time, the reaction was dilutedwith methylene chloride (20 mL), quenched with sodium thiosulfate (10%,30 mL) and extracted with methylene chloride (2×20 mL). The combinedorganic layers were dried over magnesium sulfate, filtered andconcentrated. Flash chromatography (silica, methylene chloride to 1:10methanol/methylene chloride), followed by preparative HPLC gave1-[3-(methylsulfinyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(84 mg, 45%) as a white solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 2.85 (s, 3H), 6.70 (d, J=7.9 Hz, 1H),7.35-7.38 (m, 2H), 7.52-7.56 (m, 2H), 7.76 (d, J=7.7 Hz, 1H), 7.81 (t,J=7.8 Hz, 1H), 7.91-7.93 (m, 2H), 8.00 (dt, J=8.9, 1.1 Hz, 1H),8.11-8.12 (m, 1H), 8.60 (d, J=2.6 Hz, 1H), 8.96 (d, J=7.9 Hz, 1H); APCIMS m/z 377 [M+H]⁺.

Example 391-[3-(1H-Benzimidazol-2-ylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of a mixture of1-[3-(1H-benzimidazol-2-ylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-oneand1-[3-(1H-benzimidazol-2-ylsulfanyl)phenyl]-3-(1-phenyl-1H-pyrazol-3-yl)pyridazin-4(1H)-one(0.312 g, 0.68 mmol), 3-chloroperbenzoic acid (0.327 g of a 77% puresolid, 1.46 mmol) and sodium bicarbonate (0.227 g, 2.70 mmol) indichloromethane (20 mL) was stirred for 2 h at room temperature. Afterthat time, the reaction was diluted with dichloromethane (40 mL) andquenched with saturated sodium bisulfite solution (50 mL). The organiclayer was separated and the aqueous layer extracted with dichloromethane(2×60 mL) and ethyl acetate (2×50 mL). The combined organic extractswere dried (MgSO₄) and concentrated. The crude product was purified byflash chromatography (silica gel, methylene chloride to 95:5dichloromethane/methanol), followed by crystallization from methanol andpreparative reverse phase HPLC to give1-[3-(1H-benzimidazol-2-ylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(0.005 g, 2%) as a white solid.

¹H NMR (500 MHz, DMSO-d₆) δ ppm 6.64 (d, J=7.9 Hz, 1H), 7.14 (d, J=1.9Hz, 1H), 7.25-7.31 (m, 1H), 7.33-7.42 (m, 6H), 7.44 (dd, J=2.4, 8.2 Hz,1H), 7.64-7.75 (m, 3H), 7.83 (d, J=1.9 Hz, 1H), 8.04 (d, J=7.9 Hz, 1H),8.14 (t, J=1.9 Hz, 1H), 8.91 (d, J=7.9 Hz, 1H), 14.17 (br s, 1H); ESI MSm/z 495 [M+H]⁺; mp 160-161° C.

Example 403-(4-Phenyl-4H-1,2,4-triazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbohydrazide(0.2 g, 0.67 mmol) and N,N-dimethylformamide dimethylacetal (0.09 mL,0.67 mmol) in acetonitrile (2 mL) was heated at 55° C. for 45 min. Afterthat time, acetic acid (2 mL) and aniline (0.06 mL, 0.66 mmol) wereadded and the temperature was increased to 125° C. for an additional 2h. During this time, the acetonitrile was allowed to distill-off. Thereaction was then concentrated to a dark residue and the crude productpurified by column chromatography (silica gel, ethyl acetate to 4:1ethyl acetate/methanol) to give3-(4-phenyl-4H-1,2,4-triazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.137 g, 53%) as a light yellow oil that crystallized upon standing.

¹H NMR (300 MHz, CDCl₃) δ ppm 6.67 (1H, d, J=8.0 Hz), 7.30-7.41 (2H, m),7.41-7.52 (3H, m), 7.57-7.72 (4H, m), 8.28 (1H, d, J=8.0 Hz), 8.43 (1H,s); APCI MS m/z 384 [C₁₉H₁₂F₃N₅O+H]⁺; mp 103-104° C.

Example 413-(5-Methyl-4-phenyl-4H-1,2,4-triazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbohydrazide(0.207 g, 0.69 mmol) and N,N-dimethylacetamide dimethylacetal (0.1 mL,0.68 mmol) in acetonitrile (2 mL) was heated at 60° C. for 2.5 h. Afterthat time, acetic acid (2 mL) and aniline (0.06 mL, 0.66 mmol) wereadded and the temperature was increased to 125° C. for an additional 2hours. During this time, the acetonitrile was allowed to distill-off.The reaction was then concentrated to a dark residue and the crudeproduct purified by column chromatography (silica gel, ethyl acetate to4:1 ethyl acetate/methanol) to give a yellow solid that wasrecrystallized from ethyl acetate/hexanes to give3-(5-methyl-4-phenyl-4H-1,2,4-triazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.126 g, 46%) as light yellow crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 2.40 (s, 3H), 6.63 (d, J=8.0 Hz, 1H),7.28-7.36 (m, 2H), 7.41-7.52 (m, 3H), 7.56-7.71 (m, 4H), 8.20 (d, J=8.1Hz, 1H); APCI MS m/z 398 [M+H]⁺; mp 191-192° C.

Example 423-(1-Phenyl-1H-1,2,4-triazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution ofN-[(dimethylamino)methylidene]-4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carboxamide(0.119 g, 0.35 mmol) in acetic acid (5.0 mL) was treated with phenylhydrazine (0.070 mL, 0.71 mmol). The resulting solution was heated undermicrowave heating conditions at 120° C. for 10 min. After that time thereaction was cooled to room temperature and the crude product purifiedby flash column chromatography (silica gel, ethyl acetate to 85:15 ethylacetate/methanol) to give a colorless solid that was recrystallized fromethyl acetate/hexanes to give 0.126 g (46%) of3-(1-phenyl-1H-1,2,4-triazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas colorless crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 6.75 (d, J=8.1 Hz, 1H), 7.38-7.49 (m, 5H),7.49-7.56 (m, 2H), 7.56-7.70 (m, 2H), 8.17-8.31 (m, 2H); APCI MS m/z 384[M+H]⁺; mp 167-168° C.

Example 433-(1-Phenyl-1H-tetrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[1H-benzotriazol-1-yl(phenylimino)methyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.094 g, 0.20 mmol), sodium azide (0.030 g, 0.46 mmol), andtetrabutylammonium bromide (0.015 g, 0.047 mmol) in methylene chloride(5 mL) and water (5 mL) was treated with trifluoroacetic acid (0.040 mL,0.52 mmol) and stirred 24 h at room temperature. After that time, theorganic layer was separated and the aqueous layer was extracted withmethylene chloride (3×25 mL). The combined organic extracts were washedwith saturated NaCl aqueous solution (50 mL), dried (MgSO₄), andconcentrated. The crude product purified by flash column chromatography(silica gel, 80:20 hexanes/ethyl acetate to ethyl acetate) to give anoff-white solid that was recrystallized from ethyl acetate/hexanes togive 0.034 g (56%) of3-(1-phenyl-1H-tetrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-oneas colorless crystals.

¹H NMR (300 MHz, CDCl₃) δ ppm 6.76 (d, J=8.0 Hz, 1H), 7.43-7.59 (m, 5H),7.59-7.75 (m, 4H), 8.42 (d, J=8.0 Hz, 1H); APCI MS m/z 385 [M+H]⁺; mp172-173° C.

Example 443-(1-Phenyl-1H-pyrazol-5-yl)-1-(4-piperidin-1-ylphenyl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-piperidin-1-ylphenyl)pyridazin-4(1H)-one(crude 700 mg, 1.99 mmol) in 20 mL of methanol was added phenylhydrazine(858 mg, 7.94 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give3-(1-phenyl-1H-pyrazol-5-yl)-1-(4-piperidin-1-ylphenyl)pyridazin-4(1H)-one(30 mg, 4% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 1.51-1.60 (m, 2H), 1.67-1.70 (m, 4H),3.18 (t, J=5.6 Hz, 4H), 6.65-6.70 (m, 3H), 6.74-6.77 (m, 2H), 7.37 (d,J=1.6 Hz, 1H), 7.42-7.45 (m, 5H), 7.79 (d, J=2.0 Hz, 1H), 8.08 (d, J=8.0Hz, 1H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% waterand 95% CH₃CN in 6 min, finally under these conditions for 0.5 min.)purity is >95%, Rt=3.532 min; MS Calcd.: 397, MS Found: 398 (M⁺+H).

Example 451-(4-Cyclohexylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-(4-cyclohexylphenyl)-3-[3-(dimethylamino)prop-2-enoyl]pyridazin-4(1H)-one(crude, 500 mg, 1.42 mmol) in 20 mL of methanol was addedphenylhydrazine (615 mg, 5.70 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give1-(4-cyclohexylphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(170 mg, 30% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 1.23-1.44 (m, 5H), 1.75-1.84 (m, 5H),2.47-2.53 (m, 1H), 6.69-6.73 (m, 3H), 7.11 (d, J=8.4 Hz, 2H), 7.38-7.49(m, 6H), 7.79 (d, J=2.0 Hz, 1H), 8.14 (d, J=8.0 Hz, 1H); LCMS (mobilephase: from 40% water and 60% CH₃CN to 5% water and 95% CH₃CN in 6 min,finally under these conditions for 0.5 min.) purity is >95%, Rt=2.358min; MS Calcd.: 396, MS Found: 397 (M⁺+H).

Example 464-[4-Oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]benzonitrile

To a solution of4-{3-[3-(dimethylamino)prop-2-enoyl]-4-oxopyridazin-1(4H)-yl}benzonitrile(crude, 340 mg, 1.16 mmol) in 20 mL of methanol was addedphenylhydrazine (500 mg, 4.62 mmol). The mixture was refluxed for 4 hand concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1N HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give4-[4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]benzonitrile (18mg, 4% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.74 (d, J=8.0 Hz, 2H), 6.88 (d, J=8.8Hz, 2H), 7.40-7.52 (m, 5H), 7.57 (dd, J=8.8, 2.0 Hz, 2H), 7.81 (d, J=2.0Hz, 1H), 8.20 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from 80% water and20% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under theseconditions for 0.5 min.) purity is >95%, Rt=3.077 min; MS Calcd.: 339,MS Found: 340 (M⁺+H).

Example 471-[4-(Methylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[4-(methylsulfonyl)phenyl]pyridazin-4(1H)-one(crude 615 mg, 1.77 mmol) in 20 mL of methanol was added phenylhydrazine(765 mg, 7.08 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-[4-(methylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(42 mg, 6% for two steps) as a yellow solid.

¹H NMR (400 MHz, DMSO-d₆): δ ppm 3.26 (s, 3H), 6.69 (d, J=8.0 Hz, 1H),7.27-7.30 (m, 3H), 7.41-7.43 (m, 2H), 7.48-7.52 (m, 3H), 7.84-7.89 (m,3H), 8.94 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from 90% water and 10%CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under these conditionsfor 0.5 min.) purity is >90%, Rt=3.102 min; MS Calcd.: 392, MS Found:393 (M⁺+H).

Example 481-[4-(Morpholin-4-ylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[4-(morpholin-4-ylsulfonyl)phenyl]pyridazin-4(1H)-one(crude 355 mg, 0.85 mmol) in 20 mL of methanol was added phenylhydrazine(367 mg, 3.40 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give1-[4-(morpholin-4-ylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(60 mg, 15% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 2.97 (t, J=4.8 Hz, 4H), 3.74 (t, J=4.8Hz, 4H), 6.73 (d, J=8.0 Hz, 1H), 6.91 (dd, J=7.2, 1.6 Hz, 2H), 7.39-7.48(m, 6H), 7.61-7.64 (m, 2H), 7.80 (d, J=1.6 Hz, 1H), 8.22 (d, J=8.0 Hz,1H); LCMS (mobile phase: from 80% water and 20% CH₃CN to 5% water and95% CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.035 min; MS Calcd.: 463, MS Found: 464 (M⁺+H).

Example 49 4-[4-Oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]benzamide

To a solution of4-{3-[3-(dimethylamino)prop-2-enoyl]-4-oxopyridazin-1(4H)-yl}benzamide(crude 682 mg, 2.19 mmol) in 20 mL of methanol was added phenylhydrazine(946 mg, 8.76 mmol). The mixture was refluxed for 4 h and concentrated.The residue was dissolved in dichloromethane (20 mL), washed with 1N HClaqueous solution and brine, dried over Na₂SO₄, and concentrated underreduced pressure. The residue was purified by prep-HPLC to give4-[4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]benzamide (50mg, 6% for two steps) as a yellow solid.

¹H NMR (400 MHz, CDCl₃): δ ppm 6.75 (d, J=8.0 Hz, 1H), 6.87 (d, J=8.4Hz, 2H), 7.25-7.26 (m, 1H), 7.41-7.49 (m, 5H), 7.74 (d, J=8.8 Hz, 2H),7.82 (d, J=2.0 Hz, 1H), 8.23 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from90% water and 10% CH₃CN to 5% water and 95% CH₃CN in 6 min, finallyunder these conditions for 0.5 min.) purity is >95%, Rt=2.663 min; MSCalcd.: 357, MS Found: 358 (M⁺+H).

Example 505-Methyl-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H-one

A microwave vial containing3-[3-(dimethylamino)prop-2-enoyl]-5-methyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.215 g, 0.61 mmol) and phenylhydrazine (0.24 mL, 2.44 mmol) in aceticacid (3 mL) was heated at 120° C. for 10 min. The crude material wasconcentrated and dissolved in ethyl acetate (20 mL). The organic layerwas washed with saturated sodium bicarbonate aqueous solution (3×10 mL),dried (Na₂SO₄), filtered and concentrated to provide a crude residue.The residue was purified by flash column chromatography (silica gel;35:65 ethyl acetate/hexanes to ethyl acetate) to provide5-methyl-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.0545 g, 23%) as an off-white solid.

¹H NMR (300 MHz, DMSO-d₆) δ ppm 2.06 (s, 3H), 7.22 (d, J=2.1 Hz, 1H),7.37-7.48 (m, 6H), 7.52 (s, 1H), 7.59 (t, J=8.1 Hz, 1H), 7.68-7.71 (m,1H), 7.83 (d, J=1.8 Hz, 1H) 9.00 (s, 1H); APCI MS m/z 397 [M+H]⁺; mp147-150° C.

Example 513-(3-Methyl-1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[3-(dimethylamino)but-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.270 g, 0.77 mmol) and phenyl hydrazine (0.200 mL, 2.0 mmol) in aceticacid (5.0 mL) was heated under microwave conditions at 120° C. for 10min. After this time, the reaction was cooled to room temperature andconcentrated onto silica gel. The crude product purified by columnchromatography (silica gel, 50:50 ethyl acetate/hexanes to ethylacetate) to separate the two isomers, followed by preparative reversephase HPLC and crystallization from diethyl ether to give3-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.048 g, 16%) as a white solid. ¹H NMR (300 MHz, CDCl₃) δ ppm 2.42 (s,3H), 6.73 (d, J=7.9 Hz, 1H), 6.99 (dd, J=1.7, 8.1 Hz, 1H), 7.18 (br s,1H), 7.21 (s, 1H), 7.30-7.49 (m, 6H), 7.55 (d, J=7.8 Hz, 1H), 8.19 (d,J=7.9 Hz, 1H); APCI MS m/z 397 [M+H]⁺; mp 167-168° C.

Example 521-(2-Fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of 3-acetyl-1-(2-fluorophenyl)-5-methoxypyridazin-4(1H)-one(1.89 g, 7.2 mmol) in N,N-dimethylformamide dimethyl acetal (20 mL) wasrefluxed for 6 h. After cooling to room temperature, the reactionmixture was concentrated under reduced pressure.

A solution of the residue and phenylhydrazine (2.34 mL, 21.6 mmol) inAcOH (20 mL) was refluxed for 2 h. After cooling to room temperature,the reaction mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt, washed successively with 1 M HCl aqueoussolution, 1 M NaOH aqueous solution, and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/AcOEt (1/2) andrecrystallized from MeOH/H₂O to give the title compound (1.53 g, 59%yield) as off-white crystals: mp 163-165° C.; ¹H NMR (300 MHz, CDCl₃): δppm 3.90 (3H, s), 6.43 (1H, dt, J=1.5, 7.9 Hz), 6.98-7.04 (1H, m), 7.18(1H, ddd, J=1.1, 8.3, 11.3 Hz), 7.28-7.46 (7H, m), 7.78 (1H, d, J=1.9Hz), 7.81 (1H, d, J=2.3 Hz). LC-MS (ESI) m/z 363 [M+H]⁺. Anal. Calcd forC₂₀H₁₅FN₄O₂: C, 66.29; H, 4.17; N, 15.46. Found: C, 66.09; H, 4.22; N,15.42.

Example 531-[2-(Difluoromethoxy)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of1-[2-(difluoromethoxy)phenyl]-3-[3-(dimethylamino)prop-2-enoyl]-5-methoxypyridazin-4(1H)-one(0.50 g, 1.369 mmol) and phenylhydrazine (0.269 mL, 2.74 mmol) in AcOH(5 mL) was refluxed for 2 h. After cooling to room temperature, themixture was concentrated under reduced pressure. The residue was dilutedwith AcOEt, washed successively with 1 M HCl aqueous solution, saturatedNaHCO₃ aqueous solution, and brine, dried over MgSO₄, and concentratedunder reduced pressure. The residue was purified by silica gel columnchromatography eluting with hexane/AcOEt (7/3-0/10) to give the titlecompound (0.38 g, 68% yield) as an off-white amorphous solid: ¹H NMR(300 MHz, CDCl₃): δ ppm 3.88 (3H, s), 6.37 (1H, t, J=72.3 Hz), 6.57 (1H,dd, J=8.1, 1.7 Hz), 7.09-7.16 (1H, m), 7.22-7.25 (2H, m), 7.34-7.42 (6H,m), 7.76-7.78 (2H, m). LC-MS (ESI) m/z 411 [M+H]⁺. Anal. Calcd. forC₂₁H₁₆F₂N₄O₃: C, 61.15; H, 4.07; N, 13.79. Found: C, 61.23; H, 4.11; N,13.71.

Example 545-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[3-(dimethylamino)prop-2-enoyl]-5-methoxy-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(3.41 g, 9.29 mmol) and phenylhydrazine (1.83 mL, 18.6 mmol) in AcOH (25mL) was refluxed for 2 h. After cooling to room temperature, thereaction mixture was concentrated under reduced pressure. The residuewas diluted with AcOEt, washed successively with 1 M HCl aqueoussolution, 1 M NaOH aqueous solution, and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with AcOEt and crystallized fromhexane/AcOEt to give the title compound (2.70 g, 71% yield) as colorlesscrystals: mp 139-141° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.98 (3H, s),7.05 (1H, dd, J=1.9, 7.9 Hz), 7.19 (1H, s), 7.34-7.47 (7H, m), 7.56 (1H,d, J=7.9 Hz), 7.80 (1H, d, J=1.9 Hz), 7.92 (1H, s). LC-MS (ESI) m/z 413[M+H]⁺. Anal. Calcd for C₂₁H₁₅F₃N₄O₂: C, 61.17; H, 3.67; N, 13.59.Found: C, 61.15; H, 3.65; N, 13.57.

Example 551-(2-Fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-(2-fluoro-4-iodophenyl)-5-methoxypyridazin-4(1H)-one (2.02 g,5.2 mmol) and N,N-dimethylformamide dimethyl acetal (30 mL) was refluxedfor 6 h. After cooling to room temperature, the reaction mixture wasconcentrated under reduced pressure.

A solution of the residue and phenylhydrazine (1.54 mL, 15.6 mmol) inAcOH (20 mL) was refluxed for 2 h. After cooling to room temperature,the reaction mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt, washed successively with 1 M HCl aqueoussolution, 1 M NaOH aqueous solution, and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with AcOEt and recrystallized fromMeOH to give the title compound (1.14 g, 45% yield) as pale yellowcrystals: mp 194-196° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.90 (3H, s),6.04 (1H, t, J=8.5 Hz), 7.30-7.47 (7H, m), 7.54 (1H, dd, J=1.9, 10.6Hz), 7.76 (1H, d, J=2.3 Hz), 7.78 (1H, d, J=2.3 Hz). LC-MS (ESI) m/z 489[M+H]⁺. Anal. Calcd for C₂₀H₁₄FIN₄O₂: C, 49.20; H, 2.89; N, 11.47.Found: C, 48.94; H, 3.01; N, 11.54.

Example 561-[2-Fluoro-4-(trifluoromethyl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.50 mmol), FSO₂CF₂CO₂Me (0.318 mL, 2.5 mmol), HMPA (0.435 mL,2.5 mmol), and CuI (114 mg, 0.6 mmol) in DMF (2.5 mL) was stirred for 24h at 90° C. under Ar atmosphere. After cooling to room temperature, thereaction mixture was poured into water and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was purified by basic silica gel columnchromatography eluting with hexane/AcOEt (1/1) and recrystallized fromhexane/AcOEt to give the title compound (71.7 mg, 33% yield) asoff-white crystals: mp 169-171° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.92(3H, s), 6.42-6.47 (1H, m), 7.22-7.26 (1H, m), 7.37-7.49 (7H, m), 7.80(1H, d, J=1.9 Hz), 7.84 (1H, d, J=2.3 Hz). LC-MS (ESI) m/z 431 [M+H]⁺.Anal. Calcd for C₂₁H₁₄F₄N₄O₂: C, 58.61; H, 3.28; N, 13.02. Found: C,58.50; H, 3.36; N, 12.93.

Example 571-(2-Fluoro-4-morpholin-4-ylphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), morpholine (0.053 mL, 0.6 mmol), Pd₂(dba)₃ (18.3 mg,0.02 mmol), Xantphos (46.3 mg, 0.08 mmol), and NaOtBu (67.3 mg, 0.7mmol) in 1,4-dioxane (2.5 mL) was stirred for 2 h at 90° C. under Aratmosphere. After cooling to room temperature, the reaction mixture waspoured into water and extracted with AcOEt. The extract was washed withbrine, dried over MgSO₄, and concentrated under reduced pressure. Theresidue was purified by basic silica gel column chromatography elutingwith AcOEt and recrystallized from MeOH/H₂O to give the title compound(148 mg, 66% yield) as off-white crystals: mp 226-228° C.; ¹H NMR (300MHz, CDCl₃): δ ppm 3.16-3.19 (4H, m), 3.83-3.87 (4H, m), 3.89 (3H, s),6.31 (1H, t, J=9.0 Hz), 6.45 (1H, dd, J=2.6, 9.0 Hz), 6.58 (1H, dd,J=2.6, 14.7 Hz), 7.26 (1H, d, J=1.9 Hz), 7.33-7.45 (5H, m), 7.74 (1H, d,J=2.3 Hz), 7.77 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 448 [M+H]⁺. Anal.Calcd for C₂₄H₂₂FN₅O₃: C, 64.42; H, 4.96; N, 15.65. Found: C, 64.33; H,4.98; N, 15.59.

Example 585-Hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

TMSCl (3.17 mL, 25 mmol) was added at room temperature to a solution ofNaI (3.75 g, 25 mmol) in CH₃CN (150 mL). After stirring for 30 min,5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(2.06 g, 5 mmol) was added to the resulting suspension. The mixture wasstirred for 30 min at room temperature and then refluxed for 1 h. Aftercooling to room temperature, the reaction mixture was poured into waterand extracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was washedwith hexane/AcOEt (1/1) and recrystallized from MeOH/H₂O to give thetitle compound (1.68 g, 84% yield) as a colorless powder: mp 246-248°C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 7.17 (1H, d, J=1.9 Hz), 7.33-7.46(5H, m), 7.53-7.64 (3H, m), 7.71 (1H, d, J=7.5 Hz), 7.83 (1H, d, J=1.9Hz), 8.83 (1H, s). Anal. Calcd for C₂₀H₁₃F₃N₄O₂: C, 60.30; H, 3.29; N,14.07. Found: C, 60.09; H, 3.33; N, 14.02.

Example 595-Ethoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A suspension of5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(100 mg, 0.25 mmol), iodoethane (0.040 mL, 0.50 mmol), and K₂CO₃ (104mg, 0.75 mmol) in DMF (1 mL) was stirred for 24 h at room temperature.The reaction mixture was poured into water and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was purified by basic silica gel columnchromatography eluting with hexane/AcOEt (1/1) to give the titlecompound (94.1 mg, 88% yield) as an off-white amorphous solid: ¹H NMR(300 MHz, CDCl₃): δ ppm 1.52 (3H, t, J=6.8 Hz), 4.21 (2H, q, J=6.8 Hz),7.03 (1H, dd, J=1.9, 7.9 Hz), 7.18 (1H, s), 7.33-7.46 (7H, m), 7.55 (1H,d, J=7.9 Hz), 7.80 (1H, d, J=1.9 Hz), 7.94 (1H, s). LC-MS (ESI) m/z 427[M+H]⁺. Anal. Calcd for C₂₂H₁₇F₃N₄O₂: C, 61.97; H, 4.02; N, 13.14.Found: C, 61.82; H, 4.15; N, 13.17.

Example 605-(1-Methylethoxy)-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A suspension of5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(100 mg, 0.25 mmol), 2-iodopropane (0.050 mL, 0.50 mmol), and K₂CO₃ (104mg, 0.75 mmol) in DMF (1 mL) was stirred for 20 h at 60° C. The reactionmixture was poured into water and extracted with AcOEt. The extract waswashed with brine, dried over MgSO₄, and concentrated under reducedpressure. The residue was purified by basic silica gel columnchromatography eluting with hexane/AcOEt (1/1) and crystallized fromhexane/AcOEt to give the title compound (79.5 mg, 72% yield) ascolorless prisms: mp 137-139° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 1.38(6H, d, J=6.4 Hz), 4.96-5.09 (1H, m), 7.05 (1H, dd, J=1.9, 7.9 Hz), 7.18(1H, s), 7.33-7.46 (7H, m), 7.55 (1H, d, J=7.9 Hz), 7.80 (1H, d, J=1.9Hz), 8.01 (1H, s). LC-MS (ESI) m/z 441 [M+H]⁺. Anal. Calcd forC₂₃H₁₉F₃N₄O₂: C, 62.72; H, 4.35; N, 12.72. Found: C, 62.74; H, 4.40; N,12.81.

Example 615-(Cyclopropylmethoxy)-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A suspension of5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(100 mg, 0.25 mmol), (bromomethyl)cyclopropane (0.048 mL, 0.50 mmol),and K₂CO₃ (104 mg, 0.75 mmol) in DMF (1 mL) was stirred for 20 h at roomtemperature. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/AcOEt (1/1) andcrystallized from MeOH to give the title compound (103 mg, 91% yield) ascolorless prisms: mp 72-78° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 0.32-0.47(2H, m), 0.60-0.76 (2H, m), 1.26-1.39 (1H, m), 4.06 (2H, d, J=7.2 Hz),7.04 (1H, dd, J=2.3, 8.3 Hz), 7.18 (1H, s), 7.33-7.46 (7H, m), 7.55 (1H,d, J=7.9 Hz), 7.80 (1H, d, J=1.9 Hz), 7.99 (1H, s). LC-MS (ESI) m/z 453[M+H]⁺. Anal. Calcd for C₂₄H₁₉F₃N₄O₂.0.5H₂O: C, 62.47; H, 4.37; N,12.14. Found: C, 62.19; H, 4.41; N, 12.15.

Example 625-(Difluoromethoxy)-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(398 mg, 1.0 mmol), CF₂ClCO₂Na (305 mg, 2.0 mmol), K₂CO₃ (207 mg, 1.5mmol), DMF (2 mL), and H₂O (0.4 mL) was stirred for 6 h at 100° C. Aftercooling to room temperature, the reaction mixture was poured into waterand extracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby basic silica gel column chromatography eluting with hexane/AcOEt(3/1) and crystallized from hexane/AcOEt to give the title compound (267mg, 59% yield) as colorless prisms: mp 132-134° C.; ¹H NMR (300 MHz,CDCl₃): δ ppm 7.06 (1H, dd, J=2.3, 8.3 Hz), 7.16-7.66 (10H, m), 7.82(1H, d, J=1.9 Hz), 8.33 (1H, s). LC-MS (ESI) m/z 449 [M+H]⁺. Anal. Calcdfor C₂₁H₁₃F₅N₄O₂: C, 56.26; H, 2.92; N, 12.50. Found: C, 55.98; H, 2.82;N, 12.43.

Example 631-(2-Fluorophenyl)-5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

TMSCl (1.27 mL, 10 mmol) was added at room temperature to a solution ofNaI (1.50 g, 10 mmol) in CH₃CN (60 mL). After stirring for 30 min,1-(2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(0.725 g, 2 mmol) was added to the resulting suspension. The mixture wasstirred for 30 min at room temperature and then refluxed for 1 h. Aftercooling to room temperature, the reaction mixture was poured into waterand extracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was washedwith hexane/AcOEt (1/1) and recrystallized from MeOH/H₂O to give thetitle compound (0.648 g, 93% yield) as off-white prisms: mp 218-220° C.;¹H NMR (300 MHz, DMSO-d₆): δ ppm 6.99 (1H, d, J=1.9 Hz), 7.10 (1H, dt,J=1.5, 7.9 Hz), 7.21-7.26 (1H, m), 7.32-7.54 (7H, m), 7.80 (1H, d, J=1.9Hz), 8.44 (1H, d, J=2.6 Hz). Anal. Calcd for C₁₉H₁₃FN₄O₂: C, 65.51; H,3.76; N, 16.08. Found: C, 65.73; H, 3.88; N, 16.24.

Example 645-(Difluoromethoxy)-1-(2-fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluorophenyl)-5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(557 mg, 1.6 mmol), CF₂ClCO₂Na (488 mg, 3.2 mmol), K₂CO₃ (332 mg, 2.4mmol), DMF (3 mL), and H₂O (0.6 mL) was stirred overnight at 100° C.After cooling to room temperature, the reaction mixture was poured intowater and extracted with AcOEt. The extract was washed with brine, driedover MgSO₄, and concentrated under reduced pressure. The residue waspurified by basic silica gel column chromatography eluting withhexane/AcOEt (2/1) and crystallized from hexane/AcOEt to give the titlecompound (485 mg, 76% yield) as colorless prisms: mp 109-114° C.; ¹H NMR(300 MHz, CDCl₃): δ ppm 6.46 (1H, dd, J=1.5, 7.9 Hz), 7.00-7.06 (1H, m),7.08-7.59 (9H, m), 7.80 (1H, d, J=1.9 Hz), 8.20 (1H, s). LC-MS (ESI) m/z399 [M+H]⁺. Anal. Calcd for C₂₀H₁₃F₃N₄O₂: C, 60.30; H, 3.29; N, 14.07.Found: C, 60.50; H, 3.41; N, 14.20.

Example 655-(2-Methoxyethoxy)-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A suspension of5-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(100 mg, 0.25 mmol), 2-bromoethyl methyl ether (0.070 mL, 0.75 mmol),and K₂CO₃ (104 mg, 0.75 mmol) in DMF (1 mL) was stirred for 24 h at roomtemperature. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/AcOEt (1/2) to givethe title compound (89.9 mg, 79% yield) as a pale yellow amorphoussolid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.45 (3H, s), 3.78-3.81 (2H, m),4.42-4.44 (2H, m), 7.02 (1H, dd, J=1.9, 7.9 Hz), 7.20 (1H, s), 7.34-7.45(7H, m), 7.55 (1H, d, J=7.9 Hz), 7.80 (1H, d, J=1.9 Hz), 8.29 (1H, s).LC-MS (ESI) m/z 457 [M+H]⁺. Anal. Calcd for C₂₃H₁₉F₃N₄O₃.0.25H₂O: C,59.93; H, 4.26; N, 12.16. Found: C, 59.87; H, 4.09; N, 12.15.

Example 665-(Methoxymethyl)-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-acetyl-5-(methoxymethyl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(1.39 g, 4.26 mmol) in N,N-dimethylformamide dimethyl acetal (15 mL) wasrefluxed for 4 h. After cooling to room temperature, the reactionmixture was poured into water and extracted with AcOEt three times. Thecombined extracts were washed with brine, dried over MgSO₄, andconcentrated under reduced pressure.

A solution of the residue and phenylhydrazine (1.18 mL, 12 mmol) in MeOH(15 mL) was refluxed for 1 h. After cooling to room temperature, thereaction mixture was poured into 1 M HCl aqueous solution and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/AcOEt (2/1) andrecrystallized from hexane/AcOEt to give the title compound (759 mg, 42%yield) as a pale yellow solid: mp 137-139° C.; ¹H NMR (300 MHz, CDCl₃):δ ppm 3.55 (3H, s), 4.53 (2H, d, J=1.1 Hz), 7.06 (1H, dd, J=1.9, 7.9Hz), 7.19 (1H, s), 7.35-7.45 (7H, m), 7.55 (1H, d, J=7.9 Hz), 7.81 (1H,d, J=1.9 Hz), 8.34 (1H, t, J=1.1 Hz). LC-MS (ESI) m/z 427 [M+H]⁺. Anal.Calcd for C₂₂H₁₇F₃N₄O₂: C, 61.97; H, 4.02; N, 13.14. Found: C, 61.60; H,4.05; N, 13.07.

Example 675-Bromo-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of3-acetyl-5-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (332mg, 0.92 mmol) and N,N-dimethylformamide dimethyl acetal (3.3 mL) washeated to reflux for 1 h. The mixture was concentrated in vacuo. To theresidue were added AcOH (3.3 mL) and phenylhydrazine (0.181 mL, 1.84mmol). The mixture was heated to reflux for 90 min. To the mixture wasadded phenylhydrazine (0.091 mL, 0.92 mmol). The mixture was heated toreflux for 90 min. The mixture was diluted with 1 M HCl aqueoussolution, extracted with AcOEt, washed with saturated NaHCO₃ aqueoussolution, dried over MgSO₄, filtered, concentrated in vacuo and purifiedby column chromatography on basic silica gel (hexane/AcOEt=50/50 to0/100) and by HPLC to yield the title compound (151 mg, 35% yield) as awhite solid: mp 145-146° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 7.27 (1H,d, J=1.9 Hz), 7.35-7.52 (6H, m), 7.54-7.64 (2H, m), 7.73 (1H, d, J=8.0Hz), 7.85 (1H, d, J=1.9 Hz), 9.52 (1H, s). Anal. Calcd forC₂₀H₁₂BrF₃N₄O: C, 52.08; H, 2.62; N, 12.15. Found: C, 52.07; H, 2.75; N,12.28.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=60/40)→1.20 min (A/B=60/40)→4.75 min(A/B=0/100)→7.75 min (A/B=0/100)→7.85 min (A/B=60/40)→8.50 min(A/B=60/40)

Flow rate: 70 mL/min

Detector: UV 220 nm

Concentration: 98 mg/mL

Inject volume: 825 μL

Example 681-[4-(Benzyloxy)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of3-acetyl-1-[4-(benzyloxy)-2-fluorophenyl]-5-methoxypyridazin-4(1H)-one(5.82 g, 15.8 mmol) in N,N-dimethylformamide dimethyl acetal (50 mL) wasrefluxed for 2 h. After cooling to room temperature, the reactionmixture was concentrated under reduced pressure.

A solution of the residue and phenylhydrazine (3.11 mL, 31.6 mmol) inAcOH (50 mL) was refluxed for 2 h. After cooling to room temperature,the reaction mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt, washed successively with 1 M HCl aqueoussolution, 1 M NaOH aqueous solution, and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was washed with AcOEtand then purified by basic silica gel column chromatography eluting withTHF. Recrystallization from MeOH/H₂O gave the title compound (5.57 g,75% yield) as a pale yellow solid: mp 181-183° C.; ¹H NMR (300 MHz,CDCl₃): δ ppm 3.89 (3H, s), 5.06 (2H, s), 6.35 (1H, t, J=9.0 Hz), 6.60(1H, ddd, J=1.1, 2.6, 9.0 Hz), 6.74 (1H, dd, J=2.6, 12.8 Hz), 7.28 (1H,d, J=1.9 Hz), 7.31-7.45 (10H, m), 7.72 (1H, d, J=2.6 Hz), 7.78 (1H, d,J=1.9 Hz). LC-MS (ESI) m/z 469 [M+H]⁺. Anal. Calcd for C₂₇H₂₁FN₄O₃: C,69.22; H, 4.52; N, 11.96. Found: C, 69.04; H, 4.60; N, 11.98.

Example 696-Hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

Chlorotrimethylsilane (0.46 mL, 3.6 mmol) was added to a solution ofsodium iodide (0.55 g, 0.73 mmol) in MeCN (20 mL) at room temperature.After stirring for 30 min,5-methoxy-6-(1-phenyl-1H-pyrazol-5-yl)-2-[3-(trifluoromethyl)phenyl]pyridazin-3(2H)-one (0.30 g, 0.73 mmol) was added to the resulting suspension. Themixture was stirred at room temperature for 1 h, and then refluxed for 3h. After cooling to room temperature, the mixture was poured into waterand extracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was washedwith diisopropyl ether/hexane and recrystallized from AcOEt/hexane togive the title compound (0.21 g, 73% yield) as white crystals: mp241-243° C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 6.16 (1H, s), 6.88 (1H, d,J=1.9 Hz), 7.36-7.42 (3H, m), 7.45-7.54 (4H, m), 7.59 (1H, t, J=7.9 Hz),7.70 (1H, d, J=7.9 Hz), 7.82 (1H, d, J=1.9 Hz), 12.23 (1H, brs). LC-MS(ESI) m/z 399 [M+H]⁺. Anal. Calcd for C₂₀H₁₃F₃N₄O₂: C, 60.30; H, 3.29;N, 14.07. Found: C, 60.35; H, 3.37; N, 14.10.

Example 703-[1-Phenyl-3-(trifluoromethyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of ethyl trifluoroacetate (0.139 mL, 1.17 mmol) in methyltert-butyl ether (1 mL) was added NaOMe (28% in MeOH, 245 mg, 1.27 mmol)at room temperature. To the mixture was added a solution of3-acetyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (300 mg, 1.06mmol) in THF (1.5 mL) and methyl tert-butyl ether (1.5 mL) at roomtemperature. The mixture was stirred at room temperature for 2 days. Themixture was diluted with 1 M HCl aqueous solution, extracted with AcOEt,washed with brine, dried over Na₂SO₄, filtered and concentrated invacuo. To the residue were added phenylhydrazine (0.209 mL, 2.12 mmol)and AcOH (3.5 mL). The mixture was heated to reflux for 90 min. Themixture was diluted with 1 M HCl aqueous solution, extracted with AcOEt,washed with NaHCO₃ aqueous solution, dried over MgSO₄, filtered,concentrated in vacuo, purified by column chromatography on silica gel(hexane/AcOEt=50/50 to 0/100), crystallized with AcOEt/hexane andpurified by HPLC to yield the title compound (9.6 mg, 2% yield) as awhite solid: mp 190-191° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.73 (1H,d, J=7.9 Hz), 7.37-7.81 (10H, m), 8.97 (1H, d, J=8.3 Hz). Anal. Calcdfor C₂₁H₁₂F₆N₄O: C, 56.01; H, 2.69; N, 12.44. Found: C, 55.70; H, 2.81;N,12.23.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=52/48)→10.00 min (A/B=52/48)→10.50 min(A/B=0/100)→12.50 min (A/B=0/100)→12.60 min (A/B=52/48)→13.00 min(A/B=52/48)

Flow rate: 20 mL/min

Detector: UV 220 nm

Concentration: 100 mg/mL

Inject volume: 100 μL

Example 713-(4-Methyl-1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a suspension of3-propanoyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (384 mg,1.30 mmol) in methyl formate (3.8 mL) was added NaOMe (28% in MeOH, 326mg, 1.69 mmol) at room temperature. The mixture was stirred at roomtemperature for 3.5 h. The mixture was diluted with water and 1 M HClaqueous solution, extracted with AcOEt, washed with brine, dried overNa₂SO₄, filtered, concentrated in vacuo and crystallized withAcOEt/hexane. To the solid were added phenylhydrazine (0.405 mL, 4.12mmol) and MeOH (6.7 mL). The mixture was heated to reflux for 3.5 h. Themixture was diluted with 1 M HCl aqueous solution, extracted with AcOEt,washed with saturated NaHCO₃ aqueous solution, dried over Na₂SO₄,filtered, concentrated in vacuo, purified by column chromatography onsilica gel (hexane/AcOEt=50/50 to 0/100) and crystallized withAcOEt/heptane to yield the title compound (161 mg, 39% yield) as a paleyellow solid: mp 208-211° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 2.09 (3H,s), 6.62 (1H, d, J=8.0 Hz), 7.26-7.35 (3H, m), 7.35-7.44 (2H, m),7.64-7.85 (5H, m), 8.95 (1H, d, J=8.2 Hz). Anal. Calcd for C₂₁H₁₅F₃N₄O:C, 63.63; H, 3.81; N, 14.14. Found: C, 63.46; H, 3.92; N, 13.98.

Example 723-(4-Fluoro-1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(49.0 mg, 0.128 mmol) and selectfluor (45.4 mg, 0.128 mmol) in MeCN (1mL) was stirred at room temperature for 6 days. To the mixture was addedselectfluor (45.4 mg, 0.128 mmol) at room temperature. The mixture wasstirred at room temperature for 1 day. To the mixture was addedselectfluor (45.4 mg, 0.128 mmol) at room temperature. The mixture wasstirred at room temperature for 1 day. To the mixture was addedselectfluor (45.4 mg, 0.128 mmol) at room temperature. The mixture wasstirred at room temperature for 1 day. To the mixture was addedselectfluor (272 mg, 0.768 mmol) at room temperature. The mixture wasstirred at room temperature for 3 days. The mixture was diluted withbrine, extracted with AcOEt, dried over MgSO₄, filtered, concentrated invacuo, purified by column chromatography on silica gel(hexane/AcOEt=50/50 to 0/100) and crystallized with AcOEt/hexane toyield the title compound (11.7 mg, 23% yield) as a pale yellow solid: mp156-158° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.67 (1H, d, J=8.2 Hz),7.33-7.50 (5H, m), 7.63-7.83 (4H, m), 7.97 (1H, d, J=4.1 Hz), 8.96 (1H,d, J=8.0 Hz).

Example 733-(3-Phenyl-1-trityl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

nBuLi (1.6 M solution in hexane, 25 mL, 40 mmol) was added dropwise at−78° C. to a solution of 4-bromo-3-phenyl-1-trityl-1H-pyrazole (7.96 g,20.6 mmol) and B(OiPr)₃ (6.92 mL, 30 mmol) in THF (75 mL). Afterstirring for 1 h, the reaction mixture was allowed to warm to 0° C.,quenched with saturated NH₄Cl aqueous solution, and extracted withAcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with hexane/AcOEt (2/1-0/1) andcrystallized from MeOH to give crude(3-phenyl-1-trityl-1H-pyrazol-4-yl)boronic acid (5.73 g) as a whitesolid.

A mixture of 3-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(319 mg, 1.0 mmol), (3-phenyl-1-trityl-1H-pyrazol-4-yl)boronic acid (645mg, 1.5 mmol), Pd(PPh₃)₄ (58 mg, 0.05 mmol), Na₂CO₃ (318 mg, 3.0 mmol),DME (7.5 mL), and H₂O (1.5 mL) was refluxed overnight under Aratmosphere. After cooling to room temperature, the reaction mixture waspoured into water and extracted with AcOEt. The extract was washed withbrine, dried over MgSO₄, and concentrated under reduced pressure. Theresidue was purified by silica gel column chromatography eluting withhexane/AcOEt (1/1) and crystallized from MeOH to give the title compound(418 mg, 67% yield) as a white solid: mp 216-218° C.; ¹H NMR (300 MHz,CDCl₃): δ ppm 6.58 (1H, d, J=7.9 Hz), 7.08 (1H, dd, J=2.3, 7.9 Hz),7.23-7.39 (20H, m), 7.47-7.54 (3H, m), 8.17 (1H, d, J=7.9 Hz), 8.67 (1H,s). LC-MS (ESI) m/z 625 [M+H]⁺. Anal. Calcd for C₃₉H₂₇F₃N₄O: C, 74.99;H, 4.36; N, 8.97. Found: C, 74.84; H, 4.39; N, 9.01.

Example 743-(3-Phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of3-(3-phenyl-1-trityl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(1.50 g, 2.4 mmol), TFA (5 mL), and CH₂Cl₂ (15 mL) was stirred overnightat room temperature. The reaction mixture was alkalinized with 1 M NaOHaqueous solution and extracted with AcOEt. The extract was washed withbrine, dried over MgSO₄, and concentrated under reduced pressure. Theresidue was recrystallized from MeOH to give the title compound (751 mg,82% yield) as a white solid: mp 206-208° C.; ¹H NMR (300 MHz, DMSO-d₆):δ ppm 6.58 (1H, d, J=7.9 Hz), 7.37-7.67 (9H, m), 8.33 (0.35H, brs), 8.65(0.65H, brs), 8.91 (1H, d, J=7.9 Hz), 13.17-13.46 (1H, m). LC-MS (ESI)m/z 383 [M+H]⁺. Anal. Calcd for C₂₀H₁₃F₃N₄O.0.35H₂O: C, 61.81; H, 3.55;N, 14.42. Found: C, 61.83; H, 3.61; N, 14.49.

Example 753-(1-Methyl-5-phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

Example 763-(1-Methyl-3-phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A suspension of3-(3-phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(325 mg, 0.85 mmol), iodomethane (0.081 mL, 1.3 mmol), and K₂CO₃ (235mg, 1.7 mmol) in DMF (3 mL) was stirred overnight at room temperature.The reaction mixture was poured into water and extracted with AcOEt. Theextract was washed with water and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with AcOEt and recrystallized fromhexane/AcOEt to give3-(1-methyl-5-phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(100 mg, 30% yield) as a white solid: mp 193-195° C.; ¹H NMR (300 MHz,CDCl₃): δ ppm 3.74 (3H, s), 6.61 (1H, d, J=7.9 Hz), 6.91 (1H, dd, J=2.3,8.3 Hz), 7.25 (1H, s), 7.33-7.40 (3H, m), 7.45-7.52 (4H, m), 8.12 (1H,d, J=7.9 Hz), 8.67 (1H, s). LC-MS (ESI) m/z 397 [M+H]⁺. Anal. Calcd forC₂₁H₁₅F₃N₄O: C, 63.63; H, 3.81; N, 14.14. Found: C, 63.56; H, 3.88; N,14.09.

Further elution followed by recrystallization from hexane/AcOEt afforded3-(1-methyl-3-phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(66 mg, 20% yield) as a white solid: mp 181-183° C.; ¹H NMR (300 MHz,CDCl₃): δ ppm 4.00 (3H, s), 6.67 (1H, d, J=7.9 Hz), 7.06 (1H, dd, J=2.3,8.3 Hz), 7.35-7.40 (5H, m), 7.49-7.55 (3H, m), 8.21 (1H, d, J=7.9 Hz),8.70 (1H, s). LC-MS (ESI) m/z 397 [M+H]⁺. Anal. Found: C, 63.56; H,3.85; N, 14.14.

Example 773-[1-(1-Methylethyl)-3-phenyl-1H-pyrazol-4-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

Example 783-[1-(1-Methylethyl)-5-phenyl-1H-pyrazol-4-yl]-1-[3-(trifluoromethyl)phenl]pyridazin-4(1H)-one

A suspension of3-(3-phenyl-1H-pyrazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(325 mg, 0.85 mmol), 2-iodopropane (0.130 mL, 1.3 mmol), and K₂CO₃ (235mg, 1.7 mmol) in DMF (3 mL) was stirred overnight at 50° C. The reactionmixture was poured into water and extracted with AcOEt. The extract waswashed with water and brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was purified by basic silica gel columnchromatography eluting with AcOEt followed by separation by preparativeHPLC to give the title compounds.

3-[1-(1-Methylethyl)-3-phenyl-1H-pyrazol-4-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one:a white solid (27.8 mg, 8% yield, crystallized from hexane/AcOEt); mp138-140° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 1.60 (6H, d, J=6.8 Hz),4.53-4.67 (1H, m), 6.66 (1H, d, J=7.9 Hz), 7.04 (1H, dd, J=2.1, 8.1 Hz),7.34-7.41 (5H, m), 7.49-7.57 (3H, m), 8.21 (1H, d, J=7.9 Hz), 8.74 (1H,s). LC-MS (ESI) m/z 425 [M+H]⁺. Anal. Calcd for C₂₃H₁₉F₃N₄O: C, 65.09;H, 4.51; N, 13.20. Found: C, 64.68; H, 4.50; N, 12.98.

3-[1-(1-Methylethyl)-5-phenyl-1H-pyrazol-4-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one:a white solid (17.0 mg, 5% yield, recrystallized from hexane/AcOEt); mp183-186° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 1.45 (6H, d, J=6.4 Hz),4.25-4.38 (1H, m), 6.60 (1H, d, J=7.9 Hz), 6.87 (1H, dd, J=2.1, 8.1 Hz),7.25 (1H, s), 7.32-7.38 (3H, m), 7.45-7.52 (4H, m), 8.11 (1H, d, J=7.9Hz), 8.69 (1H, s). LC-MS (ESI) m/z 425 [M+H]⁺. Anal. Found: C, 64.95; H,4.59; N, 13.14.

Preparative HPLC was performed at the conditions described below.

Column: YMC CombiPrep Pro C18 RS (50×20 mmI.D. S-5 μm, 8 nm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=64/36)→1 min (A/B=64/36)→30 min (A/B=64/36)→30.30min (A/B=0/100)→33.30 min (A/B=0/100)→30.60 min (A/B=64/36)→35 min(A/B=64/36)

Flow rate: 25 mL/min

Detector: UV 220 nm

Concentration: 100 mg/mL

Inject volume: 0.150 mL

Retention time: 20.9 min (example 77) and 24.5 min (example 78)

Example 793-(3-Phenylisoxazol-4-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of3-ethynyl-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (104 mg,0.391 mmol) and N-hydroxybenzenecarboximidoyl chloride (122 mg, 0.782mmol) in THF (5 mL) was added Et₃N (0.108 mL, 0.782 mmol) at 0° C. Thesuspension was stirred at room temperature for 14 h. The reaction wasquenched with water. The mixture was extracted with AcOEt, washed withbrine, dried over Na₂SO₄, filtered, concentrated in vacuo, purified bycolumn chromatography on silica gel (hexane/AcOEt=50/50 to 0/100) and onbasic silica gel (hexane/AcOEt=50/50 to 43/57) and crystallized withAcOEt/heptane to yield the title compound (82.4 mg, 55% yield) as awhite solid: mp 217-219° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.87 (1H,d, J=8.0 Hz), 7.50-7.59 (3H, m), 7.86-7.92 (2H, m), 7.94-8.02 (3H, m),8.15-8.26 (2H, m), 9.09 (1H, d, J=8.2 Hz). Anal. Calcd for C₂₀H₁₂F₃N₃O₂:C, 62.67; H, 3.16; N, 10.96. Found: C, 62.60; H, 3.19; N, 10.95.

Example 803-(4-Phenyl-1,3-oxazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbaldehyde(52.8 mg, 0.197 mmol) in MeCN (0.4 mL) were addedN-methylidene-1-[(4-methylphenyl)sulfonyl]-1-phenylmethanamine (53.8 mg,0.197 mmol) and K₂CO₃ (35.4 mg, 0.256 mmol) at room temperature. Thesuspension was stirred at room temperature for 1 day. The suspension wasdiluted with water, extracted with AcOEt, washed with brine, dried overMgSO₄, filtered, concentrated in vacuo, purified by columnchromatography on silica gel (hexane/AcOEt=90/10 to 0/100) andcrystallized with AcOEt/hexane to yield the title compound (18.6 mg, 25%yield) as a solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.75 (1H, d, J=8.5Hz), 7.33-7.43 (3H, m), 7.64-7.70 (2H, m), 7.72-7.83 (2H, m), 7.92-8.01(2H, m), 8.65 (1H, s), 9.02 (1H, d, J=7.7 Hz). Anal. Calcd forC₂₀H₁₂F₃N₃O₂.0.2H₂O: C, 62.08; H, 3.23; N, 10.86. Found: C, 62.08; H,3.38; N, 10.67.

Example 813-(2-Phenyl-1H-imidazol-1-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of 3-amino-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(200 mg, 0.783 mmol) and glyoxal (40% solution, 0.0895 mL, 0.783 mmol)in MeOH (2 mL) was stirred at room temperature for 20 h. To the solutionwere added benzaldehyde (0.159 mL, 1.57 mmol) and NH₄Cl (84 mg, 1.57mmol). The mixture was heated to reflux for 90 min. To the mixture wasadded H₃PO₄ (0.106 mL). The mixture was heated to reflux for 24 h. Themixture was diluted with water, extracted with AcOEt, washed with NaHCO₃aqueous solution, dried over Na₂SO₄, filtered, concentrated in vacuo,purified by column chromatography on silica gel (hexane/AcOEt=50/50 to0/100) and on basic silica gel (hexane/AcOEt=50/50 to 0/100) andrecrystallized with AcOEt/heptane to yield the title compound (9.3 mg,3% yield) as a white solid: mp 204-205° C. ¹H NMR (DMSO-d₆, 300 MHz): δppm 6.82 (1H, d, J=8.0 Hz), 7.20 (1H, d, J=1.6 Hz), 7.33-7.41 (3H, m),7.44-7.50 (2H, m), 7.62 (1H, s), 7.64-7.81 (4H, m), 9.06 (1H, d, J=8.0Hz). Anal. Calcd for C₂₀H₁₃F₃N₄O: C, 62.83; H, 3.43; N, 14.65. Found: C,62.50; H, 3.64; N, 14.56.

Example 825-Methoxy-3-(2-phenyl-1H-imidazol-1-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-amino-5-methoxy-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one (300mg, 1.05 mmol) and glyoxal (40% solution, 0.240 mL, 2.10 mmol) in MeOH(3 mL) was stirred at room temperature for 24 h. To the solution wereadded benzaldehyde (0.428 mL, 4.21 mmol) and NH₄Cl (225 mg, 4.21 mmol).The mixture was heated to reflux for 2 h. To the mixture was added H₃PO₄(0.142 mL). The mixture was heated to reflux for 20 h. The mixture wasdiluted with water and saturated NaHCO₃ aqueous solution, extracted withAcOEt, dried over Na₂SO₄, filtered, concentrated in vacuo, purified bycolumn chromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100)and by HPLC and recrystallized with AcOEt/hexane to yield the titlecompound (126 mg, 29% yield) as a white solid: mp 167-170° C. ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.94 (3H, s), 7.19 (1H, d, J=1.5 Hz),7.31-7.49 (5H, m), 7.61 (1H, d, J=1.5 Hz), 7.68-7.91 (4H, m), 8.80 (1H,s). Anal. Calcd for C₂₁H₁₅F₃N₄O₂.0.7H₂O: C, 59.35; H, 3.89; N, 13.18.Found: C, 59.28; H, 3.69; N, 13.12.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=90/10)→1.20 min (A/B=90/10)→4.75 min(A/B=0/100)→7.75 min (A/B=0/100)→7.85 min (A/B=90/10)→8.50 min(A/B=90/10)

Flow rate: 70 mL/min

Detector: UV 220 nm

Concentration: 94 mg/mL

Inject volume: 600 μL

Example 833-(4-Phenyl-1H-imidazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbaldehyde(129 mg, 0.479 mmol) and NH₃ (30% aqueous solution, 0.168 mL, 1.29 mmol)in THF (1.5 mL) was stirred at room temperature for 4 h. To the mixturewere addedN-methylidene-1-[(4-methylphenyl)sulfonyl]-1-phenylmethanamine (131 mg,0.479 mmol) and piperazine (41.3 mg, 0.479 mmol) at room temperature.The mixture was stirred at room temperature for 2 days. The mixture wasdiluted with water and saturated NaHCO₃ aqueous solution, extracted withAcOEt, dried over Na₂SO₄, filtered, concentrated in vacuo, purified bycolumn chromatography on basic silica gel (hexane/AcOEt=40/60 to 0/100and AcOEt/MeOH=100/0 to 70/30) and recrystallized with AcOEt/hexane toyield the title compound (85.6 mg, 47% yield) as a pale yellow solid: ¹HNMR (DMSO-d₆, 300 MHz): δ ppm 6.70 (1H, d, J=7.7 Hz), 7.22-7.44 (3H, m),7.57-7.85 (7H, m), 8.97 (1H, d, J=8.0 Hz), 12.75 (1H, s). Anal. Calcdfor C₂₀H₁₃F₃N₄O..0.7H₂O: C, 60.82; H, 3.67; N, 14.19. Found: C, 60.79;H, 3.76; N,13.84.

Example 843-(1-Methyl-4-phenyl-1H-imidazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of4-oxo-1-[3-(trifluoromethyl)phenyl]-1,4-dihydropyridazine-3-carbaldehyde(129 mg, 0.479 mmol) and MeNH₂ (40% aqueous solution, 0.050 mL, 0.575mmol) in DMF (3.5 mL) was stirred at room temperature for 90 min. To themixture were addedN-methylidene-1-[(4-methylphenyl)sulfonyl]-1-phenylmethanamine (131 mg,0.479 mmol) and K₂CO₃ (66.2 mg, 0.479 mmol) at room temperature. Themixture was stirred at room temperature for 27 h. The mixture wasdiluted with water, extracted with AcOEt, washed with NaHCO₃ aqueoussolution, dried over Na₂SO₄, filtered, concentrated in vacuo, purifiedby column chromatography on basic silica gel (hexane/AcOEt=40/60 to0/100 and AcOEt/MeOH=100/0 to 70/30) and recrystallized withAcOEt/hexane to yield the title compound (145 mg, 76% yield) as a paleyellow solid: mp 214-216° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.60 (3H,s), 6.74 (1H, d, J=8.0 Hz), 7.15-7.32 (3H, m), 7.45-7.53 (2H, m),7.71-7.89 (4H, m), 7.91-7.98 (1H, m), 9.04 (1H, d, J=8.0 Hz). Anal.Calcd for C₂₁H₁₅F₃N₄O: C, 63.63; H, 3.81; N, 14.14. Found: C, 63.50; H,3.89; N, 14.04.

Example 853-(2-Phenylfuran-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of 3-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(300 mg, 0.940 mmol), (2-phenylfuran-3-yl)boronic acid (265 mg, 1.41mmol), Na₂CO₃ (299 mg, 2.82 mmol) and Pd(PPh₃)₄(54.3 mg, 0.047 mmol) inDME (3.6 mL) and water (1.1 mL) was heated to 80° C. for 4 h under Aratmosphere. The mixture was diluted with water, extracted with AcOEt,washed with NaHCO₃ aqueous solution, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=80/20 to 0/100) and recrystallized with AcOEt/heptaneto yield the title compound (23.9 mg, 7% yield) as a pale yellow solid:mp 159-163° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.63 (1H, d, J=8.0 Hz),6.99 (1H, d, J=1.9 Hz), 7.32-7.43 (3H, m), 7.54-7.60 (2H, m), 7.69-7.76(2H, m), 7.78-7.82 (1H, m), 7.85 (1H, d, J=1.9 Hz), 7.85-7.92 (1H, m),8.96 (1H, d, J=8.0 Hz). Anal. Calcd for C₂₁H₁₃F₃N₂O₂.0.3H₂O: C, 65.05;H, 3.54; N, 7.22. Found: C, 65.20; H, 3.63; N, 7.29.

Example 863-(2-Phenylthiophen-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A mixture of 3-bromo-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(137 mg, 0.428 mmol), (2-phenylthiophen-3-yl)boronic acid (87.4 mg,0.428 mmol), Na₂CO₃ (136 mg, 1.28 mmol) and Pd(PPh₃)₄(24.7 mg, 0.021mmol) in DME (1.6 mL) and water (0.49 mL) was heated to 80° C. for 18 hunder Ar atmosphere. The mixture was diluted with water, extracted withAcOEt, washed with NaHCO₃ aqueous solution, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=80/20 to 0/100) and recrystallized with AcOEt/heptaneto yield the title compound (38.6 mg, 23% yield) as a white solid: mp167-168° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 6.62 (1H, d, J=8.0 Hz),7.30-7.41 (5H, m), 7.47 (1H, brs), 7.51 (1H, d, J=5.2 Hz), 7.55-7.72(4H, m), 8.91 (1H, d, J=8.0 Hz). Anal. Calcd for C₂₁H₁₃F₃N₂OS: C, 63.31;H, 3.29; N, 7.03. Found: C, 63.08; H, 3.37; N, 7.01.

Example 875-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-pyridin-4-ylpyridazin-4(1H)-one

A mixture of 3-acetyl-5-methoxy-1-pyridin-4-ylpyridazin-4(1H)-one (2.9g, 12 mmol) and N,N-dimethylformamide dimethyl acetal (20 mL) wasrefluxed for 3 h. The mixture was concentrated under reduced pressure.

A solution of the residue and phenylhydrazine (2.3 mL, 23 mmol) in AcOH(30 mL) was refluxed for 3 h. After stirring at room temperatureovernight, the mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt. The mixture was washed with saturatedNaHCO₃ aqueous solution and brine. The organic layer was dried overMgSO₄, filtered and concentrated under reduced pressure. The residue waspurified by basic silica gel column chromatography eluting withAcOEt/hexane (30/70-100/0) to give pale yellow crystals. The crystalswere washed with AcOEt and recrystallized from MeOH/AcOEt/hexane to givethe title compound (0.76 g, 19% yield) as white crystals: mp 195-197°C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.90 (3H, s), 7.17-7.23 (3H, m),7.35-7.50 (5H, m), 7.82 (1H, d, J=1.9 Hz), 8.52 (2H, dd, J=4.8, 1.5 Hz),8.64 (1H, s). LC-MS (ESI) m/z 346 [M+H]⁺. Anal. Calcd for C₁₉H₁₅N₅O₂: C,66.08; H, 4.38; N, 20.28. Found: C, 65.85; H, 4.30; N, 20.25.

Example 885-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-quinolin-8-ylpyridazin-4(1H)-one

A mixture of 3-bromo-5-methoxy-1-quinolin-8-ylpyridazin-4(1H)-one (70mg, 0.217 mmol),1-phenyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole(88.1 mg, 0.326 mmol), KOAc (42.6 mg, 0.434 mmol) andPdCl₂{P(t-Bu)₂(Ph-p-NMe₂)}₂ (7.7 mg, 0.0109 mmol) in BuOH (1.1 mL) andwater (0.1 mL) was heated to reflux for 16 h under Ar atmosphere. Themixture was diluted with water, extracted with AcOEt, washed withsaturated NaHCO₃ aqueous solution, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100 and AcOEt/MeOH=100/0 to 70/30) andrecrystallized with AcOEt/hexane to yield the title compound (69.9 mg,81% yield) as a white solid: mp 189-192° C. ¹H NMR (DMSO-d₆, 300 MHz): δppm 3.76 (3H, s), 6.98 (1H, s), 7.31-7.49 (6H, m), 7.58-7.73 (2H, m),7.78 (1H, d, J=1.9 Hz), 8.14 (1H, d, J=8.3 Hz), 8.54 (1H, d, J=7.9 Hz),8.67 (1H, s), 8.99 (1H, d, J=4.1 Hz). Anal. Calcd for C₂₃H₁₇N₅O₂: C,69.86; H, 4.33; N, 17.71. Found: C, 69.61; H, 4.37; N, 17.57.

Example 895-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-(1,2,3,4-tetrahydroquinolin-8-yl)pyridazin-4(1H)-onehydrochloride

A mixture of5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-quinolin-8-ylpyridazin-4(1H)-one(42.6 mg, 0.108 mmol) and PtO₂ (4.0 mg, 0.018 mmol) in TFA (1 mL) wasstirred at room temperature for 2 days under H₂ atmosphere. The mixturewas diluted with MeOH, filtered through a pad of celite, diluted withsaturated NaHCO₃ aqueous solution, concentrated in vacuo and purified bycolumn chromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100).To the residue was added 4 N HCl in AcOEt and triturated withtoluene/hexane to yield the title compound (20 mg, 43% yield) as ayellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 1.69-1.82 (2H, m), 2.70(2H, t, J=6.6 Hz), 3.12 (2H, t, J=5.3 Hz), 3.75 (3H, s), 6.41 (1H, t,J=7.6 Hz), 6.64 (1H, d, J=6.4 Hz), 6.88 (1H, d, J=1.9 Hz), 6.94 (1H, d,J=6.0 Hz), 7.12-7.44 (5H, m), 7.76 (1H, d, J=1.9 Hz), 8.14 (1H, s).

Example 901-(2,2-Difluoro-1,3-benzodioxol-4-yl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of1-(2,2-difluoro-1,3-benzodioxol-4-yl)-3-[3-(dimethylamino)prop-2-enoyl]-5-methoxypyridazin-4(1H)-one(2.0 g, 5.3 mmol) and phenylhydrazine (1.0 mL, 11 mmol) in AcOH (20 mL)was refluxed for 3 h. The mixture was concentrated under reducedpressure. The residue was diluted with AcOEt, and washed with saturatedNaHCO₃ aqueous solution and brine. The organic layer was dried overMgSO₄, filtered and concentrated under reduced pressure. The residue waschromatographed on silica gel (30/70-100/0 AcOEt/Hexane) to give yellowcrystals. The residual crystals were recrystallized from AcOEt/hexane togive the title compound (1.1 g, 51% yield) as white crystals: mp181-183° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.95 (3H, s), 6.19 (1H, dd,J=8.3, 1.1 Hz), 6.89 (1H, t, J=8.3 Hz), 6.99 (1H, dd, J=8.3, 1.1 Hz),7.36-7.47 (6H, m), 7.80 (1H, d, J=2.3 Hz), 8.07 (1H, s). LC-MS (ESI) m/z425 [M+H]⁺. Anal. Calcd for C₂₁H₁₄F₂N₄O₄: C, 59.44; H, 3.33; N, 13.22.Found: C, 59.43; H, 3.44; N, 13.22.

Example 911-(2-Fluoro-4-hydroxyphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[4-(benzyloxy)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(5.53 g, 11.8 mmol), 10% Pd—C (50% wet, 3.0 g), THF (150 mL), and MeOH(150 mL) was hydrogenated for 1.5 h at room temperature. The reactionmixture was filtered, and the filtrate was concentrated under reducedpressure. The residue was recrystallized from MeOH/H₂O to give the titlecompound (4.07 g, 91% yield) as a pale yellow solid: mp 223-224° C.; ¹HNMR (300 MHz, DMSO-d₆): δ ppm 3.75 (3H, s), 6.60 (1H, ddd, J=1.1, 2.6,8.7 Hz), 6.73 (1H, dd, J=2.6, 12.8 Hz), 6.90-6.96 (2H, m), 7.28-7.44(5H, m), 7.78 (1H, d, J=1.9 Hz), 8.39 (1H, d, J=1.9 Hz), 10.44 (1H,brs). LC-MS (ESI) m/z 379 [M+H]⁺. Anal. Calcd for C₂₀H₁₅FN₄O₃.0.5H₂O: C,62.01; H, 4.16; N, 14.46. Found: C, 62.18; H, 4.16; N, 14.49.

Example 921-[2-Fluoro-4-(trifluoromethoxy)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of3-acetyl-1-[2-fluoro-4-(trifluoromethoxy)phenyl]-5-methoxypyridazin-4(1H)-one(2.8 g, 8.1 mmol) and N,N-dimethylformamide diisopropyl acetal (8.5 mL,40 mmol) in toluene (50 mL) was refluxed for 5 h. After stirring at roomtemperature overnight, the mixture was concentrated under reducedpressure.

A solution of the residue and phenylhydrazine (2.0 mL, 20 mmol) in AcOH(30 mL) was refluxed for 3 h. After stirring at room temperatureovernight, the mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt, and washed with saturated NaHCO₃ aqueoussolution and brine. The organic layer was dried over MgSO₄, filtered andconcentrated under reduced pressure. The residue was chromatographed onsilica gel (10/90-100/0 AcOEt/hexane) to give 2.4 g of the crudeproduct.

One gram of the crude product was purified by preparative HPLC, and thecombined fraction was concentrated under reduced pressure. The residualsolution was basified with saturated NaHCO₃ aqueous solution andextracted with AcOEt. The organic layer was washed with brine, driedover MgSO₄, filtered and concentrated under reduced pressure. Theresidual crystals were recrystallized from AcOEt/hexane to give thetitle compound (0.66 g) as white crystals: mp 117-118° C.; ¹H NMR (300MHz, CDCl₃): δ ppm 3.90 (3H, s), 6.43 (1H, t, J=8.7 Hz), 6.85-6.90 (1H,m), 7.09 (1H, dd, J=11.5, 1.7 Hz), 7.34 (1H, d, J=1.9 Hz), 7.35-7.47(5H, m), 7.77 (1H, d, J=2.3 Hz), 7.78 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z447 [M+H]⁺. Anal. Calcd. for C₂₁H₁₄F₄N₄O₃: C, 56.51; H, 3.16; N, 12.55.Found: C, 56.51; H, 3.14; N, 12.61.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=90/10)→1 min (A/B=90/10)→4.75 min (A/B=0/100)→7.40min (A/B=0/100)→7.41 min (A/B=90/10)→8.50 min (A/B=90/10)

Flow rate: 70 mL/min

Detector: UV 220 nm

Concentration: 100 mg/mL

Inject volume: 10 mL

Example 933-Fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl trifluoromethanesulfonate

NaH (60% in oil, 0.552 g, 13.8 mol) was added portionwise at roomtemperature to a solution of1-(2-fluoro-4-hydroxyphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(4.01 g, 10.6 mmol) and N-phenylbis(trifluoromethanesulfonimide) (4.18g, 11.7 mmol) in THF (600 mL). After stirring for 1 h, the reactionmixture was concentrated under reduced pressure. The residue was dilutedwith AcOEt, washed with water and brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by silicagel column chromatography eluting with hexane/AcOEt (1/2) andcrystallized from hexane/AcOEt to give the title compound (4.73 g, 87%yield) as a white solid: mp 108-110° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.91 (3H, s), 6.46 (1H, t, J=9.0 Hz), 6.94 (1H, ddd, J=1.5, 2.6, 9.0Hz), 7.18 (1H, dd, J=2.6, 10.9 Hz), 7.34-7.47 (6H, m), 7.78 (1H, d,J=2.6 Hz), 7.79 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 511 [M+H]⁺. Anal.Calcd for C₂₁H₁₄F₄N₄O₅S: C, 49.42; H, 2.76; N, 10.98. Found: C, 49.30;H, 2.79; N, 10.96.

Example 941-(3-Bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-(3-bromo-2-fluorophenyl)-5-methoxypyridazin-4(1H)-one (2.98g, 8.74 mmol) in N,N-dimethylformamide dimethyl acetal (30 mL) washeated to reflux for 3.5 h. The mixture was concentrated in vacuo. Tothe residue were added AcOH (30 mL) and phenylhydrazine (1.72 mL, 17.5mmol). The mixture was heated to reflux for 4 h. The mixture was dilutedwith 1 M HCl aqueous solution, extracted with AcOEt, washed withsaturated NaHCO₃ aqueous solution, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and recrystallized with EtOH to yieldthe title compound (2.29 g, 59% yield) as a yellow solid: mp 186-191° C.¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.77 (3H, s), 6.99 (1H, d, J=1.9 Hz),7.08-7.15 (1H, m), 7.17-7.26 (1H, m), 7.28-7.47 (5H, m), 7.74-7.86 (2H,m), 8.55 (1H, d, J=2.3 Hz). Anal. Calcd for C₂₀H₁₄BrFN₄O₂: C, 54.44; H,3.20; N, 12.70. Found: C, 54.70; H, 3.30; N, 12.82.

Example 955-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)pyridazin-4(1H)-one

A mixture of3-bromo-5-methoxy-1-(2,2,6-trifluoro-1,3-benzodioxol-5-yl)pyridazin-4(1H)-one(145 mg, 0.383 mmol),1-phenyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole(155 mg, 0.575 mmol), K₂CO₃ (106 mg, 0.766 mmol) andPdCl₂{P(t-Bu)₂(Ph-p-NMe₂)}₂ (13.6 mg, 0.0192 mmol) in toluene (1.9 mL)and water (0.19 mL) was heated to reflux for 18 h under Ar. The mixturewas diluted with NaHCO₃ aqueous solution, extracted with AcOEt, driedover Na₂SO₄, filtered, concentrated in vacuo and purified by columnchromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100) andrecrystallized with AcOEt/hexane to yield the title compound (102 mg,60% yield) as a pale yellow solid: mp 200-202° C. ¹H NMR (DMSO-d₆, 300MHz): δ ppm 3.76 (3H, s), 6.97 (1H, d, J=1.9 Hz), 7.27-7.47 (6H, m),7.79 (1H, d, J=1.9 Hz), 7.86 (1H, d, J=9.4 Hz), 8.48 (1H, d, J=1.9 Hz).Anal. Calcd for C₂₁H₁₃F₃N₄O₄: C, 57.02; H, 2.96; N, 12.67. Found: C,56.94; H, 3.01; N, 12.59.

Example 965-Methoxy-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-bromo-5-methoxy-1-(2,2,3,3,7-pentafluoro-2,3-dihydro-1,4-benzodioxin-6-yl)pyridazin-4(1H)-one(200 mg, 0.466 mmol),1-phenyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole(189 mg, 0.699 mmol), K₂CO₃ (129 mg, 0.932 mmol) andPdCl₂{P(t-Bu)₂(Ph-p-NMe₂)}₂ (16.5 mg, 0.0233 mmol) in toluene (2.3 mL)and water (0.23 mL) was heated to reflux for 20 h under Ar. The mixturewas diluted with water, brine and saturated NaHCO₃ aqueous solution,extracted with AcOEt, dried over Na₂SO₄, filtered, concentrated invacuo, purified by column chromatography on basic silica gel(hexane/AcOEt=50/50 to 0/100) and recrystallized with AcOEt/hexane toyield the title compound (150 mg, 66% yield) as a white solid: mp192-194° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.76 (3H, s), 7.00 (1H, d,J=1.9 Hz), 7.28-7.48 (6H, m), 7.79 (1H, d, J=1.9 Hz), 7.93 (1H, d,J=10.5 Hz), 8.51 (1H, d, J=1.9 Hz). Anal. Calcd for C₂₂H₁₃F₅N₄O₄: C,53.67; H, 2.66; N, 11.38. Found: C, 53.73; H, 2.72; N, 11.33.

Example 971-[4-(Cyclopropylethynyl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (255 mg, 0.5 mmol), cyclopropylethylene(0.0846 mL, 1.0 mmol), i-Pr₂NEt (0.348 mL, 2.0 mmol), CuI (9.5 mg, 0.05mmol), Pd(PPh₃)₂Cl₂ (17.5 mg, 0.025 mmol) and PPh₃ (6.6 mg, 0.025 mmol)in DMF (1 mL) was heated to 40° C. for 90 min under Ar. The mixture wasdiluted with NaHCO₃ aqueous solution, extracted with AcOEt, dried overNa₂SO₄, filtered, concentrated in vacuo, purified by columnchromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100) andrecrystallized with AcOEt/hexane to yield the title compound (181 mg,85% yield) as a yellow solid: mp 145-146° C. ¹H NMR (DMSO-d₆, 300 MHz):δ ppm 0.74-0.82 (2H, m), 0.88-0.98 (2H, m), 1.58 (1H, tt, J=8.2, 5.1Hz), 3.77 (3H, s), 6.91-7.01 (2H, m), 7.20 (1H, dd, J=8.3, 1.1 Hz),7.28-7.51 (6H, m), 7.78 (1H, d, J=1.9 Hz), 8.47 (1H, d, J=1.9 Hz). Anal.Calcd for C₂₅H₁₉FN₄O₂: C, 70.41; H, 4.49; N, 13.14. Found: C, 70.33; H,4.60; N, 13.08.

Example 981-(4-Cyclopropyl-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (255 mg, 0.5 mmol), cyclopropylboronic acid(55.8 mg, 0.65 mmol), K₃PO₄ (372 mg, 1.75 mmol), Pd(OAc)₂ (5.6 mg, 0.025mmol) and tricyclohexylphosphine (14 mg, 0.05 mmol) in toluene (2.25 mL)and water (0.11 mL) was heated to 100° C. for 4 h under Ar. The mixturewas diluted with NaHCO₃ aqueous solution, extracted with AcOEt, driedover Na₂SO₄, filtered, concentrated in vacuo, purified by columnchromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100) andrecrystallized with AcOEt/hexane to yield the title compound (128 mg,64% yield) as a white solid: mp 140-142° C. ¹H NMR (DMSO-d₆, 300 MHz): δppm 0.70-0.82 (2H, m), 0.96-1.10 (2H, m), 1.94-2.09 (1H, m), 3.76 (3H,s), 6.87-7.01 (3H, m), 7.09-7.18 (1H, m), 7.28-7.50 (5H, m), 7.78 (1H,d, J=1.9 Hz), 8.44 (1H, d, J=1.9 Hz). Anal. Calcd for C₂₃H₁₉FN₄O₂: C,68.65; H, 4.76; N, 13.92. Found: C, 68.47; H, 4.82; N, 13.84.

Example 991-[4-(3,6-Dihydro-2H-pyran-4-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (459 mg, 0.9 mmol),3,6-dihydro-2H-pyran-4-boronic acid pinacol ester (210 mg, 1.0 mmol),Pd(PPh₃)₄(52 mg, 0.045 mmol), Na₂CO₃ (212 mg, 2.0 mmol), DME (4 mL), andH₂O (1 mL) was refluxed overnight under Ar atmosphere. After cooling toroom temperature, the precipitate was collected by filtration andrecrystallized from THF/MeOH to give the title compound (364 mg, 91%yield) as a white solid: mp 229-231° C.; ¹H NMR (300 MHz, DMSO-d₆): δppm 2.40-2.50 (2H, m), 3.77 (3H, s), 3.82 (2H, t, J=5.5 Hz), 4.22-4.27(2H, m), 6.43-6.48 (1H, m), 6.97 (1H, d, J=1.9 Hz), 7.02 (1H, t, J=8.7Hz), 7.29-7.46 (6H, m), 7.52 (1H, dd, J=1.9, 12.8 Hz), 7.79 (1H, d,J=1.9 Hz), 8.48 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 445 [M+H]⁺. Anal.Calcd for C₂₅H₂₁FN₄O₃: C, 67.56; H, 4.76; N, 12.61. Found: C, 67.31; H,4.58; N, 12.52.

Example 1001-[2-Fluoro-4-(tetrahydro-2H-pyran-4-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[4-(3,6-dihydro-2H-pyran-4-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(300 mg, 0.675 mmol), 10% Pd—C (50% wet, 300 mg), THF (30 mL), and MeOH(30 mL) was hydrogenated for 2 h at room temperature. The reactionmixture was filtered, and the filtrate was concentrated under reducedpressure. The residue was recrystallized from MeOH/H₂O to give the titlecompound (255 mg, 85% yield) as a white solid: mp 187-189° C.; ¹H NMR(300 MHz, CDCl₃): δ ppm 1.57-1.83 (4H, m), 2.72-2.82 (1H, m), 3.45-3.58(2H, m), 3.90 (3H, s), 4.09 (2H, td, J=3.0, 11.3 Hz), 6.35 (1H, t, J=8.3Hz), 6.86 (1H, dd, J=1.5, 8.3 Hz), 7.03 (1H, dd, J=1.9, 12.8 Hz), 7.28(1H, d, J=1.9 Hz), 7.35-7.46 (5H, m), 7.78 (1H, d, J=1.9 Hz), 7.79 (1H,d, J=2.6 Hz). LC-MS (ESI) m/z 447 [M+H]⁺. Anal. Calcd for C₂₅H₂₃FN₄O₃:C, 67.25; H, 5.19; N, 12.55. Found: C, 67.13; H, 5.13; N, 12.57.

Example 1011-[2-Fluoro-4-(3-fluoroazetidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 3-fluoroazetidine hydrochloride (66.9 mg, 0.6 mmol),NaO-t-Bu (125 mg, 1.3 mmol), Xantphos (46.3 mg, 0.08 mmol) and Pd₂(dba)₃(18.3 mg, 0.02 mmol) in 1,4-dioxane (2.5 mL) was heated to 90° C. for 13h under N₂. The mixture was diluted with NaHCO₃ aqueous solution,extracted with AcOEt, dried over Na₂SO₄, filtered, concentrated invacuo, purified by column chromatography on basic silica gel(hexane/AcOEt=50/50 to 0/100) and recrystallized with AcOEt/hexane toyield the title compound (88 mg, 40% yield) as a pale yellow solid: mp162-163° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.76 (3H, s), 3.86-4.04(2H, m), 4.12-4.29 (2H, m), 5.36-5.64 (1H, m), 6.25 (1H, dd, J=8.5, 2.1Hz), 6.48 (1H, dd, J=12.8, 2.3 Hz), 6.81-6.95 (2H, m), 7.25-7.48 (5H,m), 7.77 (1H, d, J=1.9 Hz), 8.36 (1H, d, J=1.9 Hz). Anal. Calcd forC₂₃H₁₉F₂N₅O₂: C, 63.44: H, 4.40: N, 16.08. Found: C, 63.62: H, 4.44: N,15.92.

Example 1021-[4-(3,3-Difluoroazetidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 3,3-difluoroazetidine hydrochloride (77.7 mg, 0.6mmol), NaO-t-Bu (125 mg, 1.3 mmol), Xantphos (46.3 mg, 0.08 mmol) andPd₂(dba)₃ (18.3 mg, 0.02 mmol) in 1,4-dioxane (2.5 mL) was heated to 90°C. for 16 h under Ar. The mixture was diluted with NaHCO₃ aqueoussolution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and recrystallized with AcOEt/hexaneto yield the title compound (123 mg, 54% yield) as a pale yellow solid:mp 204-206° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.76 (3H, s), 4.35 (4H,t, J=12.4 Hz), 6.36 (1H, dd, J=8.9, 2.4 Hz), 6.61 (1H, dd, J=12.8, 2.3Hz), 6.87-6.99 (2H, m), 7.25-7.49 (5H, m), 7.78 (1H, d, J=1.9 Hz), 8.38(1H, d, J=1.5 Hz). Anal. Calcd for C₂₃H₁₈F₃N₅O₂: C, 60.93; H, 4.00; N,15.45. Found: C, 61.00; H, 3.99; N, 15.50.

Example 1031-[4-(3,3-Difluoropyrrolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (204 mg, 0.4 mmol), 3,3-difluoropyrrolidinehydrochloride (71.8 mg, 0.5 mmol), Pd₂(dba)₃ (9.2 mg, 0.01 mmol),Xantphos (23.1 mg, 0.04 mmol), and NaOtBu (96.1 mg, 1.0 mmol) in1,4-dioxane (2 mL) was stirred for 3 h at 90° C. under Ar atmosphere.The reaction mixture was poured into water and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was subjected to basic silica gel columnchromatography followed by purification by preparative HPLC.Recrystallization from MeOH/H₂O gave the title compound (21.0 mg, 11%yield) as a yellow solid: mp 195-197° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm2.46-2.60 (2H, m), 3.52 (2H, t, J=7.2 Hz), 3.66 (2H, t, J=12.8 Hz), 3.89(3H, s), 6.09 (1H, dd, J=2.6, 9.0 Hz), 6.23 (1H, dd, J=2.6, 13.9 Hz),6.33 (1H, t, J=9.0 Hz), 7.25 (1H, d, J=1.9 Hz), 7.33-7.44 (5H, m), 7.71(1H, d, J=2.3 Hz), 7.77 (1H, d, J=2.3 Hz). LC-MS (ESI) m/z 468 [M+H]⁺.Anal. Calcd for C₂₄H₂₀F₃N₅O₂: C, 61.67; H, 4.31; N, 14.98. Found: C,61.51; H, 4.38; N, 14.89.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=60/40)→1 min (A/B=60/40)→4.75 min (A/B=0/100)→7.40min (A/B=0/100)→7.41 min (A/B=60/40)→8.50 min (A/B=60/40)

Flow rate: 70 mL/min

Detector: UV 220 nm

Concentration: 50 mg/mL

Inject volume: 0.150 mL

Retention time: 2.44 min

Example 1041-[2-Fluoro-4-(3,3,4,4-tetrafluoropyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(488 mg, 1.0 mmol), 3,3,4,4-tetrafluoropyrrolidine hydrochloride (215mg, 1.2 mmol), Pd₂(dba)₃ (18.3 mg, 0.02 mmol), Xantphos (46.3 mg, 0.08mmol), and NaOtBu (250 mg, 2.6 mmol) in 1,4-dioxane (5 mL) was stirredfor 6 h at 90° C. under Ar atmosphere. The reaction mixture was pouredinto water and extracted with AcOEt. The extract was washed with brine,dried over MgSO₄, and concentrated under reduced pressure. The residuewas subjected to basic silica gel column chromatography eluting withhexane/AcOEt (1/1-0/1) and crystallized from hexane/AcOEt to give thetitle compound (366 mg, 73% yield) as a white solid: mp 175-177° C.; ¹HNMR (300 MHz, CDCl₃): δ ppm 3.75-3.89 (7H, m), 6.10 (1H, ddd, J=0.8,2.6, 9.0 Hz), 6.26 (1H, dd, J=2.6, 13.6 Hz), 6.35 (1H, t, J=9.0 Hz),7.27 (1H, d, J=1.9 Hz), 7.34-7.46 (5H, m), 7.71 (1H, d, J=2.6 Hz), 7.78(1H, d, J=1.9 Hz). LC-MS (ESI) m/z 504 [M+H]. Anal. Calcd forC₂₄H₁₈F₅N₅O₂: C, 57.26; H, 3.60; N, 13.91. Found: C, 57.17; H, 3.61; N,13.79.

Example 1051-[4-(3,3-Difluoropiperidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 3,3-difluoropiperidine hydrochloride (94.6 mg, 0.6mmol), NaO-t-Bu (125 mg, 1.3 mmol), Xantphos (46.3 mg, 0.08 mmol) andPd₂(dba)₃ (18.3 mg, 0.02 mmol) in 1,4-dioxane (2.5 mL) was heated to 90°C. for 14 h under Ar. The mixture was diluted with NaHCO₃ aqueoussolution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and recrystallized with AcOEt/hexaneto yield the title compound (132 mg, 55% yield) as a yellow solid: mp182-187° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 1.68-1.81 (2H, m),1.97-2.16 (2H, m), 3.34-3.43 (2H, m), 3.67 (2H, t, J=11.9 Hz), 3.76 (3H,s), 6.73-7.10 (4H, m), 7.24-7.50 (5H, m), 7.78 (1H, d, J=1.9 Hz), 8.39(1H, d, J=1.9 Hz). Anal. Calcd for C₂₅H₂₂F₃N₅O₂: C, 62.36; H, 4.61; N,14.55. Found: C, 62.60; H, 4.60; N, 14.31.

Example 1061-[4-(4,4-Difluoropiperidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (408 mg, 0.8 mmol), 4,4-difluoropiperidinehydrochloride (158 mg, 1.0 mmol), Pd₂(dba)₃ (36.6 mg, 0.04 mmol),Xantphos (92.6 mg, 0.16 mmol), and NaOtBu (192 mg, 2.0 mmol) in1,4-dioxane (4 mL) was stirred for 3 h at 90° C. under Ar atmosphere.The reaction mixture was poured into water and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was purified by basic silica gel columnchromatography eluting with hexane/AcOEt (1/2-0/1) and crystallized fromhexane/AcOEt to give the title compound (96.0 mg, 25% yield) as ayellow-green solid: mp 192-194° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm2.01-2.14 (4H, m), 3.38-3.42 (4H, m), 3.89 (3H, s), 6.31 (1H, t, J=9.0Hz), 6.47 (1H, dd, J=2.3, 9.0 Hz), 6.61 (1H, dd, J=2.6, 14.3 Hz), 7.25(1H, d, J=1.9 Hz), 7.34-7.45 (5H, m), 7.73 (1H, d, J=2.3 Hz), 7.77 (1H,d, J=2.3 Hz). LC-MS (ESI) m/z 482 [M+H]⁺. Anal. Calcd for C₂₅H₂₂F₃N₅O₂:C, 62.36; H, 4.61; N, 14.55. Found: C, 62.13; H, 4.62; N, 14.43.

Example 1071-[2-Fluoro-4-(2-oxoazetidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), azetidin-2-one (42.6 mg, 0.6 mmol), K₃PO₄ (212 mg,1.0 mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.1 mmol) and CuI(9.5 mg, 0.05 mmol) in 1,4-dioxane (2 mL) was heated to 110° C. for 18 hunder Ar. To the mixture was added azetidin-2-one (42.6 mg, 0.6 mmol).The mixture was heated to 110° C. for 24 h under Ar. The mixture wasdiluted with NaHCO₃ aqueous solution, extracted with AcOEt, dried overNa₂SO₄, filtered, concentrated in vacuo, purified by columnchromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100) andrecrystallized with EtOH/hexane to yield the title compound (95 mg, 44%yield) as a pale yellow solid: mp 189-194° C. ¹H NMR (DMSO-d₆, 300 MHz):δ ppm 3.15 (2H, t, J=4.5 Hz), 3.68 (2H, t, J=4.5 Hz), 3.77 (3H, s), 6.96(1H, d, J=1.9 Hz), 7.06 (1H, t, J=8.7 Hz), 7.18 (1H, dd, J=8.7, 1.5 Hz),7.29-7.48 (6H, m), 7.78 (1H, d, J=1.9 Hz), 8.45 (1H, d, J=1.9 Hz). Anal.Calcd for C₂₃H₁₈FN₅O₃: C, 64.03; H, 4.21; N, 16.23. Found: C, 63.75; H,4.16; N, 16.22.

Example 1081-[2-Fluoro-4-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 2-pyrrolidinone (0.046 mL, 0.6 mmol), CuI (9.5 mg,0.05 mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.1 mmol), and K₃PO₄(212 mg, 1.0 mmol) in 1,4-dioxane (2 mL) was refluxed for 6 h under Aratmosphere. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with THF and recrystallizedfrom MeOH/H₂O to give the title compound (73.6 mg, 33% yield) as a paleyellow solid: mp 200-202° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 2.16-2.26(2H, m), 2.62-2.68 (2H, m), 3.82-3.87 (2H, m), 3.90 (3H, s), 6.40 (1H,t, J=9.0 Hz), 7.10 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.30 (1H, d, J=1.9Hz), 7.35-7.45 (5H, m), 7.77-7.83 (3H, m). LC-MS (ESI) m/z 446 [M+H]⁺.Anal. Calcd for C₂₄H₂₀FN₅O₃.0.25H₂O: C, 64.06; H, 4.59; N, 15.59. Found:C, 64.08; H, 4.57; N, 15.49.

Example 1091-[2-Fluoro-4-(2-oxo-1,3-oxazolidin-3-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 2-oxazolidone (52.2 mg, 0.6 mmol), CuI (9.5 mg, 0.05mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.1 mmol), and K₃PO₄ (212mg, 1.0 mmol) in 1,4-dioxane (2 mL) was refluxed for 1.5 h under Aratmosphere. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was washed with AcOEtand recrystallized from MeOH/H₂O to give the title compound (159 mg, 71%yield) as a pale yellow solid: mp 218-220° C.; ¹H NMR (300 MHz, CDCl₃):δ ppm 3.90 (3H, s), 4.03-4.08 (2H, m), 4.51-4.56 (2H, m), 6.42 (1H, t,J=9.0 Hz), 7.01 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.30 (1H, d, J=1.9 Hz),7.35-7.45 (5H, m), 7.66 (1H, dd, J=2.3, 13.6 Hz), 7.78 (2H, d, J=1.9Hz). LC-MS (ESI) m/z 448 [M+H]⁺. Anal. Calcd for C₂₃H₁₈FN₅O₄: C, 61.74;H, 4.06; N, 15.65. Found: C, 61.48; H, 4.07; N, 15.54.

Example 1104-{3-Fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}morpholin-3-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 3-morpholinone (60.7 mg, 0.6 mmol), CuI (9.5 mg,0.05 mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.1 mmol), and K₃PO₄(212 mg, 1.0 mmol) in 1,4-dioxane (2 mL) was refluxed for 6 h under Aratmosphere. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with AcOEt and recrystallizedfrom MeOH/H₂O to give the title compound (136 mg, 59% yield) as a whitesolid: mp 193-195° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.75-3.79 (2H, m),3.90 (3H, s), 4.04-4.07 (2H, m), 4.35 (2H, s), 6.41 (1H, t, J=9.0 Hz),7.00 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.31 (1H, d, J=2.3 Hz), 7.33-7.46(6H, m), 7.78-7.80 (2H, m). LC-MS (ESI) m/z 462 [M+H]⁺. Anal. Calcd forC₂₄H₂₀FN₅O₄: C, 62.47; H, 4.37; N, 15.18. Found: C, 62.31; H, 4.33; N,15.25.

Example 1111-[2-Fluoro-4-(1H-imidazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), imidazole (40.8 mg, 0.6 mmol), CuI (9.5 mg, 0.05mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.1 mmol), and Cs₂CO₃(326 mg, 1.0 mmol) in 1,4-dioxane (2 mL) was refluxed for 4 h under Aratmosphere. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with AcOEt/THF (1/0-0/1) andcrystallized from MeOH to give the title compound (16.5 mg, 8% yield) asa white solid: mp 235-236° C. (dec); ¹H NMR (300 MHz, CDCl₃): δ ppm 3.93(3H, s), 6.49 (1H, t, J=8.7 Hz), 7.03 (1H, ddd, J=1.1, 2.3, 8.7 Hz),7.22-7.27 (3H, m), 7.35 (1H, d, J=1.9 Hz), 7.38-7.49 (5H, m), 7.80 (1H,d, J=1.9 Hz), 7.82 (1H, d, J=2.6 Hz), 7.86 (1H, t, J=1.1 Hz). LC-MS(ESI) m/z 429 [M+H]⁺. Anal. Calcd for C₂₃H₁₇FN₆O₂: C, 64.48; H, 4.00; N,19.62. Found: C, 64.35; H, 3.90; N, 19.43.

Example 1121-[4-(3,5-Dimethylisoxazol-4-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (230 mg, 0.45 mmol),3,5-dimethylisoxazole-4-boronic acid (70 mg, 0.50 mmol), Pd(PPh₃)₄(29mg, 0.025 mmol), Na₂CO₃ (106 mg, 1.0 mmol), DME (4 mL), and H₂O (1 mL)was refluxed for 3 h under Ar atmosphere. After cooling to roomtemperature, the reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with THF and recrystallizedfrom MeOH/H₂O to give the title compound (121 mg, 59% yield) as a whitesolid: mp 200-202° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 2.27 (3H, s), 2.42(3H, s), 3.92 (3H, s), 6.49 (1H, t, J=8.3 Hz), 6.89 (1H, ddd, J=0.8,1.9, 8.3 Hz), 7.08 (1H, dd, J=1.9, 12.1 Hz), 7.32 (1H, d, J=1.9 Hz),7.35-7.47 (5H, m), 7.79 (1H, d, J=1.9 Hz), 7.85 (1H, d, J=2.3 Hz). LC-MS(ESI) m/z 458 [M+H]⁺. Anal. Calcd for C₂₅H₂₀FN₅O₃: C, 65.64; H, 4.41; N,15.31. Found: C, 65.55; H, 4.32; N, 15.33.

Example 1131-[2-Fluoro-3-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-[2-fluoro-3-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxypyridazin-4(1H)-one(243 mg, 0.708 mmol) in N,N-dimethylformamide dimethyl acetal (2.4 mL)was heated to reflux for 2 h. The mixture was concentrated in vacuo. Tothe residue were added AcOH (2.4 mL) and phenylhydrazine (0.139 mL, 1.42mmol). The mixture was heated to reflux for 2 h. The mixture was dilutedwith 1 M HCl aqueous solution, extracted with AcOEt, washed withsaturated NaHCO₃ aqueous solution, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=20/80 to 0/100) and recrystallized withEtOH/AcOEt/hexane to yield the title compound (193 mg, 62% yield) as apale yellow solid: mp 218-221° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.78(3H, s), 3.91 (3H, s), 6.97 (2H, d, J=1.9 Hz), 7.13-7.50 (6H, m),7.72-7.84 (2H, m), 7.93 (1H, s), 8.18 (1H, d, J=2.3 Hz), 8.55 (1H, d,J=1.9 Hz).

Example 1141-[2-Fluoro-4-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (230 mg, 0.45 mmol),1-methyl-1H-pyrazole-4-boronic acid pinacol ester (104 mg, 0.50 mmol),Pd(PPh₃)₄(29 mg, 0.025 mmol), Na₂CO₃ (106 mg, 1.0 mmol), DME (4 mL), andH₂O (1 mL) was refluxed overnight under Ar atmosphere. After cooling toroom temperature, the reaction mixture was poured into water andextracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby basic silica gel column chromatography eluting with THF andrecrystallized from MeOH/H₂O to give the title compound (162 mg, 81%yield) as a white solid: mp 195-197° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.91 (3H, s), 3.96 (3H, s), 6.38 (1H, t, J=8.3 Hz), 7.06 (1H, ddd,J=0.8, 1.9, 8.3 Hz), 7.23 (1H, dd, J=1.9, 12.8 Hz), 7.30 (1H, d, J=1.9Hz), 7.36-7.47 (5H, m), 7.64 (1H, s), 7.74 (1H, d, J=0.8 Hz), 7.79 (1H,d, J=1.9 Hz), 7.81 (1H, d, J=2.6 Hz). LC-MS (ESI) m/z 443 [M+H]⁺. Anal.Calcd for C₂₄H₁₉FN₆O₂: C, 65.15; H, 4.33; N, 18.99. Found: C, 65.15; H,4.30; N, 19.02.

Example 1151-[2-Fluoro-5-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-[2-fluoro-5-(1-methyl-1H-pyrazol-4-yl)phenyl]-5-methoxypyridazin-4(1H)-one(200 mg, 0.585 mmol) in N,N-dimethylformamide dimethyl acetal (2.0 mL)was heated to reflux for 3 h. The mixture was concentrated in vacuo. Tothe residue were added AcOH (2.0 mL) and phenylhydrazine (0.115 mL, 1.17mmol). The mixture was heated to reflux for 3 h. The mixture was dilutedwith 1 M HCl aqueous solution, extracted with AcOEt, washed withsaturated NaHCO₃ aqueous solution, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and by HPLC and recrystallized withEtOH/hexane to yield the title compound (118 mg, 46% yield) as a whitesolid: mp 93-102° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.78 (3H, s), 3.89(3H, s), 6.91 (1H, d, J=1.9 Hz), 7.20-7.52 (7H, m), 7.63-7.71 (1H, m),7.78 (1H, d, J=1.9 Hz), 7.83 (1H, s), 8.10 (1H, s), 8.53 (1H, d, J=1.6Hz). Anal. Calcd for C₂₄H₁₉FN₆O₂.1.3H₂O: C, 61.88; H, 4.67; N, 18.04.Found: C, 61.63; H, 4.64; N, 18.09.

Preparative HPLC was performed at the conditions described below.

Column: YMC CombiPrep Pro C18 RS (50×20 mmI.D. S-5 μm, 8 nm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=95/5)→1.00 min (A/B=95/5)→5.70 min (A/B=0/100)→7.30min (A/B=0/100)→7.40 min (A/B=95/5)→8.00 min (A/B=95/5)

Flow rate: 20 mL/min

Detector: UV 220 nm

Concentration: 89 mg/mL

Inject volume: 100 μL

Example 1161-{4-[1-(Difluoromethyl)-1H-pyrazol-4-yl]-2-fluorophenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (230 mg, 0.45 mmol),1-(difluoromethyl)-1H-pyrazole-4-boronic acid pinacol ester (122 mg,0.50 mmol), Pd(PPh₃)₄(17 mg, 0.015 mmol), Na₂CO₃ (106 mg, 1.0 mmol), DME(4 mL), and H₂O (1 mL) was refluxed for 3 h under Ar atmosphere. Aftercooling to room temperature, the reaction mixture was poured into waterand extracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby basic silica gel column chromatography eluting with AcOEt andrecrystallized from MeOH/H₂O to give the title compound (183 mg, 85%yield) as a white solid: mp 185-187° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.92 (3H, s), 6.41 (1H, t, J=8.3 Hz), 7.03-7.48 (10H, m), 7.79 (1H, d,J=1.9 Hz), 7.83 (1H, d, J=2.3 Hz), 7.91 (1H, d, J=0.8 Hz). LC-MS (ESI)m/z 479 [M+H]⁺. Anal. Calcd for C₂₄H₁₇F₃N₆O₂: C, 60.25; H, 3.58; N,17.57. Found: C, 60.19; H, 3.48; N, 17.52.

Example 1171-[2-Fluoro-4-(1,3-oxazol-2-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 2-(tributylstannanyl)-1,3-oxazole (0.209 mL, 1.0mmol) and Pd (PPh₃)₄(57.8 mg, 0.05 mmol) in 1,4-dioxane (3 mL) washeated to reflux for 11 h under Ar. The mixture was diluted with NaHCO₃aqueous solution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100 and AcOEt/MeOH=100/0 to 70/30) andrecrystallized with EtOH/hexane to yield the title compound (113 mg, 53%yield) as a yellow solid: mp 223-225° C. ¹H NMR (DMSO-d₆, 300 MHz): δppm 3.79 (3H, s), 7.02 (1H, d, J=1.9 Hz), 7.16 (1H, t, J=8.3 Hz),7.31-7.51 (6H, m), 7.77-7.83 (2H, m), 7.96 (1H, dd, J=11.5, 1.7 Hz),8.34 (1H, s), 8.55 (1H, d, J=2.6 Hz). Anal. Calcd forC₂₃H₁₆FN₅O₃.0.1H₂O: C, 64.06; H, 3.79; N, 16.24. Found: C, 63.92; H,3.67; N, 16.23.

Example 1181-(2-Fluoro-4-pyridin-2-ylphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyltrifluoromethanesulfonate (200 mg, 0.392 mmol),(2-pyridine)cyclic-triolborate lithium salt (167 mg, 0.784 mmol),2-(di-tert-butylphosphino)biphenyl (12.9 mg, 0.0431 mmol), CuI (14.9 mg,0.0784 mmol) and Pd(OAc)₂ (4.4 mg, 0.0196 mmol) in DMF (1.2 mL) washeated to 80° C. for 13 h under Ar. The mixture was diluted with NaHCO₃aqueous solution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and on silica gel (hexane/AcOEt=50/50to 0/100) and recrystallized with AcOEt/hexane to yield the titlecompound (68.9 mg, 40% yield) as a pale yellow solid: mp 206-208° C.; ¹HNMR (DMSO-d₆, 300 MHz): δ ppm 3.80 (3H, s), 7.01 (1H, d, J=1.9 Hz), 7.11(1H, t, J=8.3 Hz), 7.31-7.53 (6H, m), 7.80 (1H, d, J=1.9 Hz), 7.91-8.02(2H, m), 8.08-8.20 (2H, m), 8.55 (1H, d, J=1.9 Hz), 8.72 (1H, d, J=4.5Hz). Anal. Calcd for C₂₅H₁₈FN₅O₂: C, 68.33; H, 4.13; N, 15.94. Found: C,68.15; H, 4.18; N, 15.83.

Example 1191-[4-(3,4-Difluoro-1H-pyrrol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

KOtBu (236 mg, 2.1 mmol) was added portionwise at room temperature to asolution of1-[2-fluoro-4-(3,3,4,4-tetrafluoropyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(352 mg, 0.7 mmol) in DMSO (3.5 mL). After stirring for 30 min, thereaction mixture was poured into water and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was subjected to basic silica gel columnchromatography eluting with hexane/AcOEt (1/1-0/1) followed bypurification by preparative HPLC. Recrystallization from MeOH/H₂Oafforded the title compound (105 mg, 32% yield) as a white solid: mp212-214° C.; 1H NMR (300 MHz, CDCl₃): δ ppm 3.91 (3H, s), 6.42 (1H, t,J=9.0 Hz), 6.68-6.78 (2H, m), 6.87 (1H, ddd, J=1.1, 2.6, 9.0 Hz), 7.07(1H, dd, J=2.6, 12.4 Hz), 7.33 (1H, d, J=2.3 Hz), 7.36-7.48 (5H, m),7.78-7.79 (2H, m). LC-MS (ESI) m/z 464 [M+H]⁺. Anal. Calcd forC₂₄H₁₆F₃N₅O₂: C, 62.20; H, 3.48; N, 15.11. Found: C, 62.20; H, 3.51; N,15.01.

Preparative HPLC was performed at the conditions described below.

Column: YMC CombiPrep ODS-A (20×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0.00 min (A/B=60/40)→1.00 min (A/B=60/40)→4.75 min(A/B=0/100)→7.39 min (A/B=0/100)→7.40 min (A/B=100/0)→7.50 min(A/B=100/0)

Flow rate: 25 mL/min

Detector: UV 220 nm

Concentration: 33.3 mg/mL

Inject volume: 0.300 mL

Retention time: 2.35 min

Example 1201-[2-Fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(4.88 g, 10 mmol), pyrazole (0.681 g, 10 mmol), Cu₂O (0.143 g, 1 mmol),salicylaldoxime (0.549 g, 4 mmol), and Cs₂CO₃ (6.52 g, 20 mmol) in CH₃CN(100 mL) was refluxed for 5 h under Ar atmosphere. After cooling to roomtemperature, the reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/THF (1/2) andrecrystallized from EtOH/H₂O to give the title compound (1.90 g, 44%yield) as a pale yellow powder: mp 214-216° C.; ¹H NMR (300 MHz, CDCl₃)δ ppm 3.92 (3H, s), 6.44 (1H, t, J=9.0 Hz), 6.53 (1H, dd, J=1.9, 2.3Hz), 7.30 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.34 (1H, d, J=1.9 Hz),7.37-7.48 (5H, m), 7.61 (1H, dd, J=2.3, 12.4 Hz), 7.76 (1H, d, J=1.9Hz), 7.79 (1H, d, J=1.9 Hz), 7.82 (1H, d, J=2.3 Hz), 7.92 (1H, d, J=2.3Hz). LC-MS (ESI) m/z 429 [M+H]⁺. Anal. Calcd for C₂₃H₁₇FN₆O₂: C, 64.48;H, 4.00; N, 19.62. Found: C, 64.41; H, 4.00; N, 19.54.

Example 121 Ethyl1-{3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}-5-hydroxy-1H-pyrazole-4-carboxylate

A mixture of tert-butyl1-{3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}hydrazinecarboxylate(2.02 g, 4.1 mmol), TFA (5 mL), and CH₂Cl₂ (10 mL) was stirred for 3 hat room temperature. The reaction mixture was concentrated under reducedpressure.

A suspension of the residue, diethyl ethoxymethylenemalonate (0.829 mL,4.1 mmol), and K₂CO₃ (1.70 g, 12.3 mmol) in EtOH (20 mL) was refluxedfor 3 h. After cooling to room temperature, the reaction mixture waspoured into water and extracted with AcOEt. The extract was washed withbrine, dried over MgSO₄, and concentrated under reduced pressure. Theresidue was washed with AcOEt and recrystallized from EtOH to give thetitle compound (1.43 g, 67% yield) as a pale orange solid: mp 188-193°C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 1.41 (3H, t, J=7.2 Hz), 3.92 (3H, s),4.39 (2H, q, J=7.2 Hz), 6.45 (1H, t, J=9.0 Hz), 7.35 (1H, d, J=1.9 Hz),7.37-7.48 (5H, m), 7.55 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.77-7.82 (3H,m), 7.83 (1H, d, J=2.3 Hz). Anal. Calcd for C₂₆H₂₁FN₆O₅: C, 60.46; H,4.10; N, 16.27. Found: C, 60.28; H, 4.17; N, 16.37.

Example 1221-[2-Fluoro-4-(5-hydroxy-1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of ethyl1-{3-fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}-5-hydroxy-1H-pyrazole-4-carboxylate (1.41 g, 2.73 mmol),4 M NaOH (40 mL), and EtOH (40 mL) was refluxed for 4 h. After coolingto room temperature, conc. HCl (20 mL) was added slowly. The mixture wasstirred for 30 min at room temperature and then refluxed for 1 h. Aftercooling to room temperature, the reaction mixture was poured into waterand extracted with AcOEt. The extract was washed with brine, dried overMgSO₄, and concentrated under reduced pressure. The residue was purifiedby silica gel column chromatography eluting with AcOEt/THF (2/1) andrecrystallized from THF/MeOH to give the title compound (387 mg, 32%yield) as a pale yellow solid: mp 221-229° C.; ¹H NMR (300 MHz,DMSO-d₆): δ ppm 3.78 (3H, s), 5.57 (1H, d, J=1.5 Hz), 6.99 (1H, d, J=1.9Hz), 7.14 (1H, t, J=9.0 Hz), 7.31-7.51 (6H, m), 7.64-7.68 (1H, m),7.79-7.84 (2H, m), 8.52 (1H, d, J=1.9 Hz), 12.17 (1H, brs). LC-MS (ESI)m/z 445 [M+H]⁺.

Example 1231-{4-[5-(Difluoromethoxy)-1H-pyrazol-1-yl]-2-fluorophenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

Example 1241-{4-[2-(Difluoromethyl)-5-oxo-2,5-dihydro-1H-pyrazol-1-yl]-2-fluorophenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[2-fluoro-4-(5-hydroxy-1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(373 mg, 0.84 mmol), CF₂ClCO₂Na (256 mg, 1.68 mmol), K₂CO₃ (232 mg, 1.68mmol), DMF (2.5 mL), and H₂O (0.5 mL) was stirred for 2 h at 100° C. Thereaction mixture was poured into water and extracted with AcOEt. Theextract was washed with brine, dried over MgSO₄, and concentrated underreduced pressure. The residue was purified by basic silica gel columnchromatography eluting with AcOEt and recrystallized from AcOEt to give1-{4-[5-(difluoromethoxy)-1H-pyrazol-1-yl]-2-fluorophenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(168 mg, 40% yield) as a pale yellow solid: mp 177-179° C.; ¹H NMR (300MHz, CDCl₃): δ ppm 3.92 (3H, s), 6.07-6.08 (1H, m), 6.45 (1H, t, J=9.0Hz), 6.59 (1H, t, J=71.8 Hz), 7.34-7.47 (7H, m), 7.58 (1H, dd, J=2.3,12.4 Hz), 7.61 (1H, d, J=1.9 Hz), 7.79 (1H, d, J=1.9 Hz), 7.83 (1H, d,J=2.3 Hz). LC-MS (ESI) m/z 495 [M+H]⁺. Anal. Calcd for C₂₄H₁₇F₃N₆O₃: C,58.30; H, 3.47; N, 17.00. Found: C, 58.17; H, 3.46; N, 16.91.

Further elution followed by recrystallization from MeOH/H₂O afforded1-{4-[2-(difluoromethyl)-5-oxo-2,5-dihydro-1H-pyrazol-1-yl]-2-fluorophenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(63.5 mg, 15% yield) as a white solid: mp 161-163° C.; ¹H NMR (CDCl₃) δ3.91 (3H, s), 5.99 (1H, d, J=4.1 Hz), 6.40 (1H, t, J=60.7 Hz), 6.47 (1H,t, J=8.7 Hz), 7.09 (1H, ddd, J=1.1, 2.3, 8.7 Hz), 7.32 (1H, d, J=1.9Hz), 7.36-7.47 (6H, m), 7.79-7.81 (3H, m). LC-MS (ESI) m/z 495 [M+H]⁺.Anal. Calcd for C₂₄H₁₇F₃N₆O₃.0.5H₂O: C, 57.26; H, 3.60; N, 16.69. Found:57.38; H, 3.52; N, 16.78.

Example 1251-[2-(1-Methylethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-(1-Methylethyl)phenyl]hydrazono}pentane-2,4-dione (0.98 g, 3.98mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was stirred for 4 hours at 120° C., and thenconcentrated under reduced pressure.

To a solution of the residue in 20 mL of methanol, phenylhydrazine (1.72g, 15.93 mmol) was added, and the mixture was refluxed for 4 hours, andconcentrated. The residue was dissolved in dichloromethane (40 mL),washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (80 mg, 6% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ 1.08 (6H, d, J=7.2 Hz), 2.62-2.70 (1H,m), 6.61 (1H, d, J=7.6 Hz), 6.85 (1H, dd, J=8.0, 1.6 Hz), 7.06 (1H, d,J=1.6 Hz), 7.16-7.21 (1H, m), 7.26-7.41 (7H, m), 7.75 (1H, d, J=1.6 Hz),7.78 (1H, d, J=8.0 Hz); LCMS (mobile phase: from 70% water and 30% CH₃CNto 5% water and 95% CH₃CN in 6 min, finally under these conditions for0.5 min.) purity is 90%, Rt=3.158 min; MS Calcd.: 356; MS Found: 357[M+H]⁺.

Example 1262-[4-Oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]benzonitrile

2-[2-(1-Acetyl-2-oxopropylidene)hydrazino]benzonitrile (4.00 g, 17.47mmol) was dissolved in 40 mL of N,N-dimethylformamide dimethyl acetal,the mixture was stirred for 4 hours at 120° C., and then concentratedunder reduced pressure.

To a solution of the residue in 80 mL of methanol, phenylhydrazine (3.77g, 34.94 mmol) was added, and the mixture was refluxed for 4 hours at80° C., and concentrated. The residue was dissolved in dichloromethane(80 mL), washed with 1 M HCl aqueous solution and brine, dried overNa₂SO₄, and concentrated under reduced pressure. The residue waspurified by prep-HPLC to give the title compound (350 mg, 6% yield) as abrown solid: ¹H NMR (400 MHz, CDCl₃): δ 6.68 (1H, d, J=8.0 Hz), 6.72(1H, dd, J=8.0, 1.2 Hz), 7.32-7.40 (6H, m), 7.48-7.54 (2H, m), 7.74 (1H,dd, J=7.6, 2.0 Hz), 7.79 (1H, d, J=2.0 Hz), 8.11 (1H, d, J=7.6 Hz); LCMS(mobile phase: from 80% water and 20% CH₃CN to 5% water and 95% CH₃CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=2.881 min; MS Calcd.: 339; MS Found: 340 [M+H]⁺.

Example 1271-Biphenyl-2-yl-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-(Biphenyl-2-ylhydrazono)pentane-2,4-dione (420 mg, 1.50 mmol) wasdissolved in 4 mL of N,N-dimethylformamide dimethyl acetal, and themixture was stirred for 4 hours at 120° C., and then concentrated underreduced pressure.

To a solution of the residue in 10 mL of methanol, phenylhydrazine (648mg, 6.00 mmol) was added, and the mixture was refluxed for 4 hours at80° C., and concentrated. The residue was dissolved in dichloromethane(30 mL), washed with 1 M HCl aqueous solution and brine, dried overNa₂SO₄, and concentrated under reduced pressure. The residue waspurified by prep-HPLC to give the title compound (184 mg, 31% yield) asa yellow solid: ¹H NMR (400 MHz, CDCl₃): δ 6.25 (1H, d, J=7.6 Hz), 6.72(1H, dd, J=8.0, 0.8 Hz), 7.05-7.08 (2H, m), 7.12 (1H, d, J=2.0 Hz),7.27-7.45 (12H, m), 7.77 (1H, d, J=1.6 Hz); LCMS (mobile phase: from 70%water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally underthese conditions for 0.5 min.) purity is >95%, Rt=3.272 min; MS Calcd.:390; MS Found: 391 [M+H]⁺.

Example 1281-(2-Ethoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(2-Ethoxyphenyl)hydrazono]pentane-2,4-dione (2.00 g, 8.06 mmol) wasdissolved in 20 mL of N,N-dimethylformamide dimethyl acetal, the mixturewas stirred for 4 hours at 120° C., and then concentrated under reducedpressure.

To a solution of the residue in 60 mL of methanol, phenylhydrazine (3.48g, 32.24 mmol) was added, and the mixture was refluxed for 4 hours at80° C., and concentrated. The residue was dissolved in dichloromethane(80 mL), washed with 1 M HCl aqueous solution and brine, dried overNa₂SO₄, and concentrated under reduced pressure. The residue waspurified by prep-HPLC to give the title compound (75 mg, 2% yield) as abrown solid: ¹H NMR (400 MHz, CDCl₃): δ 1.36 (3H, t, J=6.8 Hz), 4.05(2H, q, J=6.8 Hz), 6.32 (1H, dd, J=8.0, 1.2 Hz), 6.61 (1H, d, J=7.6 Hz),6.78 (1H, td, J=7.6, 1.2 Hz), 6.94 (1H, dd, J=8.4, 1.2 Hz), 7.25-7.30(2H, m), 7.39-7.43 (5H, m), 7.78 (1H, d, J=2.0 Hz), 8.06 (1H, d, J=7.6Hz); LCMS (mobile phase: from 80% water and 20% CH3CN to 5% water and95% CH3CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.375 min; MS Calcd.: 358; MS Found: 359 [M+H]⁺.

Example 1291-[2-(1-Methylethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-(1-Methylethoxy)phenyl]hydrazono}pentane-2,4-dione (0.53 g, 2.02mmol) was dissolved in 6 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was stirred for 4 hours at 120° C., then concentratedunder reduced pressure.

To a solution of the residue in 20 mL of methanol, phenylhydrazine (0.87g, 8.08 mmol) was added, and the mixture was refluxed for 4 hours at 80°C., and concentrated. The residue was dissolved in dichloromethane (40mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (7 mg, 1% yield) as a yellow solid:¹H NMR (400 MHz, CDCl₃): δ 1.26 (6H, d, J=6.0 Hz), 4.50-4.54 (1H, m),6.37 (1H, dd, J=8.0, 1.6 Hz), 6.60 (1H, d, J=7.6 Hz), 6.79 (1H, td,J=7.6, 1.2 Hz), 6.96 (1H, dd, J=8.0, 1.2 Hz), 7.24-7.28 (2H, m),7.36-7.42 (5H, m), 7.97 (1H, d, J=2.4 Hz), 8.04 (1H, d, J=8.0 Hz); LCMS(mobile phase: from 70% water and 30% CH₃CN to 5% water and 95% CH3CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=3.151 min; MS Calcd.: 372; MS Found: 373 [M+H]⁺.

Example 1303-(1-Phenyl-1H-pyrazol-5-yl)-1-[2-(trifluoromethoxy)phenyl]pyridazin-4(1H)-one

3-{[2-(Trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (0.43 g, 1.5mmol) was dissolved in 20 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was stirred for 4 hours at 120° C., and thenconcentrated under reduced pressure.

To a solution of the residue in 40 mL of methanol, phenylhydrazine (486mg, 4.5 mmol) was added, and the mixture was refluxed for 4 hours at 80°C., and concentrated. The residue was dissolved in dichloromethane (40mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (22 mg, 4% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.67 (dt, J=8.0, 1.6 Hz, 2H),7.23-7.31 (m, 2H), 7.36-7.46 (m, 7H), 7.81 (d, J=2.0 Hz, 1H), 7.95 (d,J=8.0 Hz, 1H); LCMS (mobile phase: from 70% water and 30% CH₃CN to 5%water and 95% CH₃CN in 6 min, finally under these conditions for 0.5min.) purity is >95%, Rt=3.118 min; MS Calcd.: 398; MS Found: 399[M+H]⁺.

Example 1311-(2-Phenoxyphenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(2-Phenoxyphenyl)hydrazono]pentane-2,4-dione (1.00 g, 3.37 mmol) wasdissolved in 10 mL of N,N-dimethylformamide dimethyl acetal, and themixture was stirred for 4 hours at 120° C., then concentrated underreduced pressure.

To a solution of the residue in 30 mL of methanol, phenylhydrazine (1.46g, 13.48 mmol) was added, and the mixture was refluxed for 4 hours at80° C., and concentrated. The residue was dissolved in dichloromethane(30 mL), washed with 1 M HCl aqueous solution and brine, dried overNa₂SO₄, and concentrated under reduced pressure. The residue waspurified by prep-HPLC to give the title compound (55 mg, 4% yield) as ayellow solid: ¹H NMR (400 MHz, CDCl₃): δ 6.55 (2H, dd, J=8.0, 1.2 Hz),6.86-6.89 (2H, m), 6.94-7.01 (2H, m), 7.11-7.15 (1H, m), 7.22 (1H, d,J=1.6 Hz), 7.25-7.41 (8H, m), 7.76 (1H, d, J=2.0 Hz), 8.12 (1H, d, J=7.6Hz); LCMS (mobile phase: from 70% water and 30% CH3CN to 5% water and95% CH3CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.410 min; MS Calcd.: 406; MS Found: 407 [M+H]⁺.

Example 1321-[2-(Methylsulfinyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-(Methylsulfinyl)phenyl]hydrazono}pentane-2,4-dione (0.66 g, 2.48mmol) was dissolved in 8 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was stirred for 4 hours at 120° C., then concentratedunder reduced pressure.

To a solution of the residue in 15 mL of methanol, phenylhydrazine (1.07g, 9.92 mmol) was added, and the mixture was refluxed for 4 hours at 80°C., and concentrated. The residue was dissolved in dichloromethane (40mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (32 mg, 3% yield) as a red solid:¹H NMR (400 MHz, CDCl₃): δ 2.63 (3H, s), 6.64 (1H, d, J=7.6 Hz), 6.87(1H, d, J=2.0 Hz), 7.22 (1H, dd, J=8.0, 1.2 Hz), 7.30-7.40 (5H, m), 7.60(1H, td, J=8.0, 1.2 Hz), 7.70 (1H, t, J=8.0, 1.2 Hz), 7.80 (1H, d, J=1.6Hz), 8.07 (1H, d, J=8.0 Hz), 8.20 (1H, dd, J=7.6, 1.6 Hz); LCMS (mobilephase: from 90% water and 10% CH3CN to 5% water and 95% CH3CN in 6 min,finally under these conditions for 0.5 min.) purity is 93%, Rt=2.720min; MS Calcd.: 376; MS Found: 377 [M+H]⁺.

Example 1331-[2-(Methylsulfonyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

To a solution of1-[2-(methylsulfinyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(60% purity, 300 mg, 0.80 mmol) in 20 mL of acetic acid was added 30%H₂O₂ aqueous solution (362 mg, 3.19 mmol), and the mixture was stirredat 40° C. for 18 h. The solvents were removed under reduced pressure,water was added, extracted with AcOEt, washed with water, Na₂CO₃ aqueoussolution and brine, dried over Na₂SO₄, and then concentrated. Theresidue was purified by prep.-HPLC to give the title compound (20 mg, 6%yield) as a red solid: ¹H NMR (400 MHz, CDCl₃): δ 2.89 (3H, s), 6.60(1H, d, J=8.0 Hz), 6.96 (1H, d, J=2.0 Hz), 7.24-7.35 (4H, m), 7.41-7.43(2H, m), 7.70-7.77 (3H, m), 7.92 (1H, d, J=8.0 Hz), 8.16-8.18 (1H, m);LCMS (mobile phase: from 90% water and 10% CH3CN to 5% water and 95%CH3CN in 6 min, finally under these conditions for 0.5 min.) purityis >90%, Rt=3.073 min; MS Calcd.: 392; MS Found: 393 [M+H]⁺.

Example 1343-(1-Phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethoxy)phenyl]pyridazin-4(1H)-one

3-{[3-(Trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (0.43 g, 1.5mmol) was dissolved in 20 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was stirred for 4 hours at 120° C., and thenconcentrated under reduced pressure.

To a solution of the residue in 40 mL of methanol, phenylhydrazine (486mg, 4.5 mmol) was added, and the mixture was refluxed for 4 hours at 80°C., and concentrated. The residue was dissolved in dichloromethane (40mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (105 mg, 18% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.56 (t, J=2.0 Hz, 1H), 6.76 (d,J=8.0 Hz, 1H), 6.85-6.88 (m, 1H), 7.15-7.18 (m, 1H), 7.33-7.49 (m, 7H),7.81 (d, J=2.0 Hz, 1H), 8.16 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finallyunder these conditions for 0.5 min.) purity is >95%, Rt=3.450 min; MSCalcd.: 398; MS Found: 399 [M+H]⁺.

Example 135 N-{4-[4-Oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}acetamide

N-{4-[2-(1-Acetyl-2-oxopropylidene)hydrazino]phenyl}acetamide (500 mg,1.92 mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethylacetal, and the mixture was refluxed for 4 hours, then concentratedunder reduced pressure.

To a solution of the residue in 20 mL of methanol, phenylhydrazine (829mg, 7.68 mmol) was added, and the mixture was refluxed for 4 hours, andconcentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (51 mg, 7.2% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ 2.20 (3H, s), 6.70-6.77 (3H, m),7.41-7.44 (8H, m), 7.80 (1H, d, J=2.0 Hz), 8.13 (1H, d, J=8.0 Hz); LCMS(mobile phase: from 90% water and 10% CH3CN to 5% water and 95% CH3CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=2.870 min; MS Calcd.: 371, MS Found: 372 [M+H]⁺.

Example 1361-[4-(Dimethylamino)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[4-(Dimethylamino)phenyl]hydrazono}pentane-2,4-dione (500 mg, 2.02mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was refluxed for 4 hours, then concentrated underreduced pressure.

To a solution of the residue in 20 mL of methanol, phenylhydrazine (656mg, 6.07 mmol) was added, and the mixture was refluxed for 4 hours, andconcentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (17 mg, 2.4% yield) as a brownsolid: ¹H NMR (400 MHz, CDCl₃): δ 2.98 (6H, s), 6.53 (2H, d, J=9.2 Hz),6.67-6.70 (3H, m), 7.36 (1H, d, J=1.6 Hz), 7.41-7.46 (5H, m), 7.79 (1H,d, J=2.0 Hz), 8.07 (1H, d, J=7.6 Hz); LCMS (mobile phase: from 90% waterand 10% CH3CN to 5% water and 95% CH3CN in 6 min, finally under theseconditions for 0.5 min.) purity is >90%, Rt=3.658 min; MS Calcd.: 357,MS Found: 358 [M+H]⁺.

Example 1371-[4-(4-Methylpiperazin-1-yl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[4-(4-Methylpiperazin-1-yl)phenyl]hydrazono}pentane-2,4-dione (610mg, 2.02 mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethylacetal, and the mixture was refluxed for 4 hours, then concentratedunder reduced pressure.

To a solution of the residue in 20 mL of methanol, phenylhydrazine (872mg, 8.08 mmol) was added, and the mixture was refluxed for 4 hours, andconcentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (11 mg, 1.3% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ 2.47 (3H, s), 2.71-2.75 (4H, m), 3.28(4H, t, J=4.8 Hz), 6.67-6.77 (5H, m), 7.37-7.44 (6H, m), 7.78 (1H, d,J=2.0 Hz), 8.07 (1H, d, J=7.6 Hz); LCMS (mobile phase: from 80% waterand 20% CH3CN to 5% water and 95% CH3CN in 6 min, finally under theseconditions for 0.5 min.) purity is >95%, Rt=2.522 min; MS Calcd.: 412,MS Found: 413 [M+H]⁺.

Example 1383-(1-Phenyl-1H-pyrazol-5-yl)-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]pyridazin-4(1H)-one

3-{[4-(1H-1,2,4-Triazol-1-yl)phenyl]hydrazono}pentane-2,4-dione (500 mg,1.84 mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethylacetal, and the mixture was refluxed for 4 hours, then concentratedunder reduced pressure.

To a solution of the residue in 20 mL of methanol, phenylhydrazine (795mg, 7.36 mmol) was added, and the mixture was refluxed for 4 hours, andconcentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (33 mg, 4.7% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ 6.75 (1H, d, J=8.0 Hz), 6.93 (2H, dd,J=7.2, 2.0 Hz), 7.42-7.50 (6H, m), 7.62 (2H, dd, J=6.8, 2.0 Hz), 7.82(1H, d, J=2.0 Hz), 8.14 (1H, s), 8.21 (1H, d, J=8.4 Hz), 8.57 (1H, s);LCMS (mobile phase: from 90% water and 10% CH3CN to 5% water and 95%CH3CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=2.992 min; MS Calcd.: 381, MS Found: 382 [M+H]⁺.

Example 1393-(1-Phenyl-1H-pyrazol-5-yl)-1-[4-(trifluoromethoxy)phenyl]pyridazin-4(1H)-one

3-{[4-(Trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (1.58 g,6.124 mmol) was dissolved in 30 mL of N,N-dimethylformamide dimethylacetal, and the mixture was stirred for 4 hours at 120° C., and thenconcentrated under reduced pressure.

To a solution of the residue in 40 mL of methanol, phenylhydrazine (2.0g, 18.4 mmol) was added, and the mixture was refluxed for 4 hours at 80°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (15 mg, 0.5% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.72 (d, J=8.0 Hz, 1H), 6.81 (dd,J=6.8, 2.4 Hz, 2H), 7.13 (d, J=8.0 Hz, 2H), 7.40-7.47 (m, 6H), 7.81 (d,J=1.6 Hz, 1H), 8.14 (d, J=7.6 Hz, 1H); LCMS (mobile phase: from 60%water and 40% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally underthese conditions for 0.5 min.) purity is >95%, Rt=2.860 min; MS Calcd.:398; MS Found: 399 [M+H]⁺.

Example 1401-[2-Fluoro-3-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-Fluoro-3-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (900mg, 3.1 mmol) was dissolved in 1 mL of N,N-dimethylformamide diisopropylacetal and 2 mL of DMF and the mixture was stirred at 120° C. for 4hours, and then concentrated under reduced pressure.

To a solution of the residue in 25 mL of t-BuOH, phenylhydrazine (1 g,9.3 mmol) was added, and the mixture was stirred for 4 hours at 60° C.,and concentrated. The residue was dissolved in dichloromethane (20 mL),washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄, andconcentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (38 mg, 4% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.62-6.66 (m, 1H), 6.70 (d, J=8.0Hz, 1H), 7.15 (t, J=8.0 Hz, 1H), 7.40-7.49 (m, 6H), 7.60-7.63 (m, 1H),7.82 (d, J=2.0 Hz, 1H), 8.06 (dd, J=8.0, 2.8 Hz, 1H); LCMS (mobilephase: from 70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min,finally under these conditions for 0.5 min.) purity is >95%, Rt=3.333min; MS Calcd.: 400; MS Found: 401 [M+H]⁺.

Example 1411-(2,3-Difluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(2,3-Difluorophenyl)hydrazono]pentane-2,4-dione (900 mg, 1.16 mmol)was dissolved in 3.5 mL of N,N-dimethylformamide diisopropyl acetal and5.5 mL of DMF and the mixture was stirred at 120° C. for 4 hours, andthen concentrated under reduced pressure.

To a solution of the residue in 20 mL of t-BuOH, phenylhydrazine (376mg, 3.48 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (22 mg, 5% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.23 (td, J=6.8, 2.0 Hz, 1H), 6.66(d, J=7.6 Hz, 1H), 6.92-6.98 (m, 1H), 7.12-7.19 (m, 1H), 7.36-7.45 (m,6H), 7.79 (d, J=2.0 Hz, 1H), 8.01 (dd, J=7.6, 2.4 Hz, 1H); LCMS (mobilephase: from 70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min,finally under these conditions for 0.5 min.) purity is >95%, Rt=2.824min; MS Calcd.: 350; MS Found: 351 [M+H]⁺.

Example 1421-(2,2-Difluoro-1,3-benzodioxol-4-yl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-[(2,2-difluoro-1,3-benzodioxol-4-yl)hydrazono]pentane-2,4-dione (3.0g, 10 mmol) in N,N-dimethylformamide dimethyl acetal (30 mL) wasrefluxed for 5 h. The mixture was concentrated under reduced pressure.

A solution of the residue and phenylhydrazine (2.0 mL, 21 mmol) in AcOH(30 mL) was refluxed for 4 h. After stirring at room temperatureovernight, the mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt, and washed with saturated NaHCO₃ aqueoussolution and brine. The organic layer was dried over MgSO₄, filtered andconcentrated under reduced pressure. The residue was chromatographed onsilica gel (5/95-40/60 AcOEt/hexane) to give the title compound (2.1 g,51% yield) as white crystals: mp 105-107° C.; ¹H NMR (300 MHz, CDCl₃): δppm 6.16 (1H, dd, J=8.3, 1.1 Hz), 6.71 (1H, d, J=7.9 Hz), 6.90 (1H, d,J=8.3 Hz), 6.98 (1H, dd, J=7.9, 1.3 Hz), 7.35-7.49 (6H, m), 7.80 (1H, d,J=1.9 Hz), 8.30 (1H, d, J=7.9 Hz). LC-MS (ESI) m/z 395 [M+H]⁺. Anal.Calcd. for C₂₀H₁₂F₂N₄O₃: C, 60.92; H, 3.07; N, 14.21. Found: C, 60.91;H, 3.13; N, 14.30.

Example 1431-[2-Fluoro-4-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-Fluoro-4-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (720mg, 2.48 mmol) was dissolved in 1 mL of N,N-dimethylformamidediisopropyl acetal and 2 mL of DMF and the mixture was stirred at 120°C. for 4 hours, and then concentrated under reduced pressure.

To a solution of the residue in 20 mL of t-BuOH, phenylhydrazine (803mg, 7.44 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (16 mg, 2% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.43 (t, J=8.4 Hz, 1H), 6.68 (d,J=8.0 Hz, 1H), 7.23-7.25 (m, 1H), 7.38-7.49 (m, 7H), 7.80 (d, J=2.0 Hz,1H), 8.10 (dd, J=8.0, 2.4 Hz, 1H); LCMS (mobile phase: from 70% waterand 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally under theseconditions for 0.5 min.) purity is >95%, Rt=3.421 min; MS Calcd.: 400;MS Found: 401 [M+H]⁺.

Example 1441-[4-(Difluoromethoxy)-2-fluorophenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[4-(Difluoromethoxy)-2-fluorophenyl]hydrazono}pentane-2,4-dione (300mg, 1.04 mmol) was dissolved in 1 mL of N,N-dimethylformamidediisopropyl acetal and 2 mL of DMF and the mixture was stirred at 120°C. for 4 hours, and then concentrated under reduced pressure.

To a solution of the residue in 20 mL of t-BuOH, phenylhydrazine (337mg, 3.12 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (35 mg, 9% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.34-6.70 (m, 4H), 6.78 (d, J=9.2Hz, 1H), 6.99 (dd, J=12.0, 2.4 Hz, 1H), 7.36-7.46 (m, 5H), 7.79 (d,J=2.0 Hz, 1H), 7.97 (dd, J=8.0, 2.4 Hz, 1H); LCMS (mobile phase: from70% water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finallyunder these conditions for 0.5 min.) purity is >95%, Rt=3.065 min; MSCalcd.: 398; MS Found: 399 [M+H]⁺.

Example 1451-[2-Fluoro-4-(trifluoromethoxy)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-Fluoro-4-(trifluoromethoxy)phenyl]hydrazono}pentane-2,4-dione (200mg, 0.65 mmol) was dissolved in 1 mL of N,N-dimethylformamidediisopropyl acetal and 2 mL of DMF and the mixture was stirred at 120°C. for 4 hours, and then concentrated under reduced pressure.

To a solution of the residue in 20 mL of t-BuOH, phenylhydrazine (211mg, 1.96 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (35 mg, 13% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.44 (t, J=8.8 Hz, 1H), 6.69 (d,J=7.6 Hz, 1H), 6.90 (d, J=8.8 Hz, 1H), 7.11 (d, J=11.2 Hz, 1H),7.41-7.49 (m, 6H), 7.82 (d, J=1.6 Hz, 1H), 8.02 (dd, J=8.0, 2.4 Hz, 1H);LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.432 min; MS Calcd.: 416; MS Found: 417 [M+H]⁺.

Example 1461-(2,4-Difluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(2,4-Difluorophenyl)hydrazono]pentane-2,4-dione (550 mg, 2.29 mmol)was dissolved in 1.5 mL of N,N-dimethylformamide diisopropyl acetal and3 mL of DMF and the mixture was stirred at 120° C. for 4 hours, and thenconcentrated under reduced pressure.

To a solution of the residue in 20 mL of t-BuOH, phenylhydrazine (742mg, 6.87 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (42 mg, 5% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.36-6.41 (m, 1H), 6.66 (d, J=8.0Hz, 1H), 6.72-6.77 (m, 1H), 6.90-6.96 (m, 1H), 7.36-7.47 (m, 6H), 7.79(d, J=2.0 Hz, 1H), 7.96 (dd, J=8.0, 2.4 Hz, 1H); LCMS [mobile phase:from 70% water (0.1% TFA) and 30% CH₃CN to 5% water (0.1% TFA) and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.] purityis >95%, Rt=2.829 min; MS Calcd.: 350; MS Found: 351 [M+H]⁺.

Example 1471-(4-Chloro-2-fluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(4-Chloro-2-fluorophenyl)hydrazono]pentane-2,4-dione (1 g, 3.9 mmol)was dissolved in 1.76 mL of N,N-dimethylformamide diisopropyl acetal and3 mL of DMF and the mixture was stirred at 120° C. for 4 hours, and thenconcentrated under reduced pressure.

To a solution of the residue in 20 mL of t-BuOH, phenylhydrazine (1.26g, 11.7 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (59 mg, 4% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.27 (t, J=8.8 Hz, 1H), 6.66 (d,J=8.0 Hz, 1H), 6.96-6.99 (m, 1H), 7.20 (dd, J=10.8, 2.4 Hz, 1H),7.37-7.48 (m, 6H), 7.79 (d, J=2.0 Hz, 1H), 7.99 (dd, J=8.0, 2.4 Hz, 1H);LCMS (mobile phase: from 50% water and 50% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purity is93%, Rt=1.622 min; MS Calcd.: 366; MS Found: 367 [M+H]⁺.

Example 1481-[2-(Dimethylamino)-5-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

Example 1491-[2-Fluoro-5-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-{[2-Fluoro-5-(trifluoromethyl)phenyl]hydrazono}pentane-2,4-dione (630mg, 2.2 mmol) was dissolved in 4.6 mL of DMF and N,N-dimethylformamidediisopropyl acetal (1.0 mL, 1.1 equiv.), and the mixture was stirred for4 hours at 120° C., and then concentrated under reduced pressure.

To a solution of the residue in 20 mL of toluene, phenylhydrazine (713mg, 6.6 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (40mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give1-[2-fluoro-5-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(43 mg, 5% yield) and1-[2-(dimethylamino)-5-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(20 mg, 2% yield).

1-[2-Fluoro-5-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one:a yellow solid; ¹H NMR (400 MHz, CDCl₃): δ ppm 6.70 (d, J=8.0 Hz, 1H),6.89-6.90 (m, 1H), 7.30-7.44 (m, 7H), 7.60-7.63 (m, 1H), 7.81 (d, J=2.4Hz, 1H), 8.00 (dd, J=8.0, 2.8 Hz, 1H); LCMS (mobile phase: from 70%water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally underthese conditions for 0.5 min.) purity is >95%, Rt=3.205 min; MS Calcd.:400; MS Found: 401 [M+H]⁺.

1-[2-(Dimethylamino)-5-(trifluoromethyl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one:a white solid; ¹H NMR (400 MHz, CDCl₃): δ ppm 2.57 (s, 6H), 6.66 (d,J=8.0 Hz, 1H), 6.74 (d, J=2.0 Hz, 1H), 7.04 (d, J=8.8 Hz, 1H), 7.28 (d,J=2.4 Hz, 1H), 7.34-7.37 (m, 5H), 7.49 (dd, J=8.8, 2.0 Hz, 1H), 7.79 (d,J=2.0 Hz, 1H), 7.98 (d, J=8.0 Hz, 1H); LCMS (mobile phase: from 70%water and 30% CH₃CN to 5% water and 95% CH₃CN in 6 min, finally underthese conditions for 0.5 min.) purity is >95%, Rt=3.479 min; MS Calcd.:425; MS Found: 426 [M+H]⁺.

Example 1501-(2,5-Difluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(2,5-Difluorophenyl)hydrazono]pentane-2,4-dione (1.455 g, 6.06 mmol)was dissolved in 20 mL of DMF and then 4.3 mL of N,N-dimethylformamidediisopropyl acetal was added, and the mixture was stirred for 4 hours at120° C., and then concentrated under reduced pressure.

To a solution of the residue in 35 mL of t-BuOH, phenylhydrazine (1.96g, 18.18 mmol) was added, and the mixture was refluxed for 4 hours at80° C., and concentrated. The residue was dissolved in dichloromethane(40 mL), washed with 1 M HCl aqueous solution and brine, dried overNa₂SO₄, and concentrated under reduced pressure. The residue waspurified by prep-HPLC to give the title compound (66 mg, 3% yield) as ayellow solid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.02-6.06 (m, 1H), 6.66 (d,J=7.6 Hz, 1H), 6.97-7.02 (m, 1H), 7.11-7.17 (m, 1H), 7.32-7.52 (m, 6H),7.79 (d, J=2.0 Hz, 1H), 8.05 (dd, J=7.6, 2.4 Hz, 1H); LCMS [mobilephase: from 80% water (0.1% TFA) and 20% CH₃CN to 5% water (0.1% TFA)and 95% CH₃CN in 6 min, finally under these conditions for 0.5 min.]purity is >95%, Rt=3.347 min; MS Calcd.: 350; MS Found: 351 [M+H]⁺.

Example 151 1-(2,6-Difluorophenyl)-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

3-[(2,6-Difluorophenyl)hydrazono]pentane-2,4-dione (400 mg, 1.67 mmol)was dissolved in 1 mL of N,N-dimethylformamide di-tert-butyl acetal and2 mL of DMF and the mixture was stirred at 120° C. for 4 hours, and thenconcentrated under reduced pressure.

To a solution of the residue in 20 mL of toluene, phenylhydrazine (541mg, 5 mmol) was added, and the mixture was stirred for 4 hours at 60°C., and concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M HCl aqueous solution and brine, dried over Na₂SO₄,and concentrated under reduced pressure. The residue was purified byprep-HPLC to give the title compound (30 mg, 5% yield) as a yellowsolid: ¹H NMR (400 MHz, CDCl₃): δ ppm 6.59 (d, J=8.0 Hz, 1H), 6.98-7.03(m, 2H), 7.12 (d, J=2.0 Hz, 1H), 7.21-7.42 (m, 6H), 7.73-7.75 (m, 2H);LCMS (mobile phase: from 70% water and 30% CH₃CN to 5% water and 95%CH₃CN in 6 min, finally under these conditions for 0.5 min.) purityis >94%, Rt=2.497 min; MS Calcd.: 350; MS Found: 351 [M+H]⁺.

Example 1523-[1-(Cyclopropylmethyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(675 mg, 2 mmol), cyclopropylmethylhydrazine hydrochloride (490 mg, 4mmol), and Et₃N (0.558 mL, 4 mmol) in MeOH (20 mL) was refluxed for 2 h.After cooling to room temperature, the reaction mixture was poured into1 M HCl aqueous solution and extracted with AcOEt. The extract waswashed with brine, dried over MgSO₄, and concentrated under reducedpressure. The residue was purified by basic silica gel columnchromatography eluting with AcOEt and recrystallized from hexane/AcOEtto give the title compound (315 mg, 44% yield) as a pale yellow solid:mp 155-157° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 0.35-0.44 (2H, m),0.45-0.57 (2H, m), 1.24-1.40 (1H, m), 4.37 (2H, d, J=6.8 Hz), 6.76 (1H,d, J=7.9 Hz), 7.37 (1H, d, J=1.9 Hz), 7.61 (1H, d, J=1.9 Hz), 7.68-7.74(2H, m), 7.78-7.83 (1H, m), 7.94 (1H, s), 8.28 (1H, d, J=7.9 Hz). Anal.Calcd for C₁₈H₁₅F₃N₄O: C, 60.00; H, 4.20; N, 15.55. Found: C, 60.07; H,4.24; N, 15.56.

Example 1533-(1-Benzyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.675 g, 2.0 mmol), benzylhydrazine dihydrochloride (1.56 g, 8.0 mmol),and Et₃N (2.23 mL, 16 mmol) in MeOH (20 mL) was refluxed for 3 h. Aftercooling to room temperature, the reaction mixture was poured into 1 MHCl aqueous solution and extracted with AcOEt. The extract was washedwith brine, dried over MgSO₄, and concentrated under reduced pressure.The residue was recrystallized from hexane/AcOEt to give the titlecompound (375 mg, 47% yield) as a white solid: mp 156-157° C.; ¹H NMR(300 MHz, CDCl₃): δ ppm 5.75 (2H, s), 6.70 (1H, d, J=7.9 Hz), 6.84-6.91(2H, m), 7.18-7.24 (3H, m), 7.32-7.37 (1H, m), 7.47-7.53 (2H, m),7.64-7.67 (2H, m), 7.70 (1H, d, J=1.9 Hz), 8.15 (1H, d, J=7.9 Hz). Anal.Calcd for C₂₁H₁₅F₃N₄O: C, 63.63; H, 3.81; N, 14.14. Found: C, 63.63; H,3.85; N, 14.16.

Example 1543-[1-(4-Methoxybenzyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

A solution of3-[3-(dimethylamino)prop-2-enoyl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(675 mg, 2 mmol), (4-methoxybenzyl)hydrazine hydrochloride (755 mg, 4mmol), and Et₃N (0.558 mL, 4 mmol) in MeOH (20 mL) was refluxed for 3 h.After cooling to room temperature, the reaction mixture was poured into1 M HCl aqueous solution and extracted with AcOEt. The extract waswashed with brine, dried over MgSO₄, and concentrated under reducedpressure. The residue was purified by basic silica gel columnchromatography eluting with AcOEt and recrystallized from hexane/AcOEtto give the title compound (367 mg, 43% yield) as an off-white solid: mp159-161° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.73 (3H, s), 5.67 (2H, s),6.69-6.75 (3H, m), 6.81-6.86 (2H, m), 7.41 (1H, d, J=1.9 Hz), 7.45-7.51(1H, m), 7.54-7.59 (1H, m), 7.65-7.71 (3H, m), 8.17 (1H, d, J=7.9 Hz).LC-MS (ESI) m/z 427 [M+H]⁺. Anal. Calcd for C₂₂H₁₇F₃N₄O₂: C, 61.97; H,4.02; N, 13.14. Found: C, 61.95; H, 4.14; N, 13.08.

Example 1553-(1-Thiophen-2-yl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a mixture of copper (I) oxide (0.028 g, 0.20 mmol), salicylaldoxime(0.11 g, 0.78 mmol), Cs₂CO₃ (0.64 g, 2.0 mmol) and3-(1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.30 g, 0.98 mmol) in MeCN (8 mL) was added 2-iodothiophene (0.16 mL,1.5 mmol), and the mixture was stirred at 90° C. for 1 day. The mixturewas diluted with AcOEt and water, and filtered. The filtrate waspartitioned between AcOEt and water. The organic layer was washed withbrine, dried over MgSO₄, filtered and concentrated under reducedpressure. The residue was chromatographed on silica gel (20/80-100/0AcOEt/hexane) to give yellow crystals. The crystals were purified bypreparative HPLC and recrystallized from AcOEt/hexane to give the titlecompound (11 mg, 3% yield) as off-white crystals: ¹H NMR (300 MHz,CDCl₃): δ ppm 6.75 (1H, d, J=7.9 Hz), 6.95 (1H, dd, J=5.5, 3.8 Hz), 7.01(1H, dd, J=3.8, 1.3 Hz), 7.23 (1H, dd, J=5.5, 1.3 Hz), 7.31 (1H, d,J=8.7 Hz), 7.40 (1H, brs), 7.42 (1H, d, J=1.9 Hz), 7.51-7.57 (1H, m),7.62 (1H, d, J=7.9 Hz), 7.81 (1H, d, J=1.9 Hz), 8.21 (1H, d, J=7.9 Hz).LC-MS (ESI) m/z 389 [M+H]⁺.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=90/10)→1 min (A/B=90/10)→4.75 min (A/B=0/100)→7.40min (A/B=0/100)→7.41 min (A/B=90/10)→8.50 min (A/B=90/10)

Flow rate: 70 mL/min

Detector: UV 220 nm

Example 1563-(1-Thiophen-3-yl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a mixture of copper (I) oxide (0.028 g, 0.20 mmol), salicylaldoxime(0.11 g, 0.78 mmol), Cs₂CO₃ (0.64 g, 2.0 mmol) and3-(1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.30 g, 0.98 mmol) in MeCN (8 mL) was added 3-iodothiophene (0.15 mL,1.5 mmol), and the mixture was stirred at 90° C. for 2 days and at roomtemperature for 4 days. The mixture was diluted with AcOEt and water,and filtered. The filtrate was partitioned between AcOEt and water. Theorganic layer was washed with brine, dried over MgSO₄, filtered andconcentrated under reduced pressure. The residue was chromatographed onsilica gel (20/80-100/0 AcOEt/hexane) to give yellow crystals. Thecrystals were purified by preparative HPLC and recrystallized fromAcOEt/hexane to give the title compound (7 mg, 2% yield) as off-whitecrystals: ¹H NMR (300 MHz, CDCl₃): δ ppm 6.75 (1H, d, J=7.9 Hz), 7.12(1H, dd, J=4.5, 1.9 Hz), 7.24 (1H, s), 7.30-7.34 (2H, m), 7.36 (1H, d,J=1.9 Hz), 7.41 (1H, s), 7.50-7.57 (1H, m), 7.59-7.64 (1H, m), 7.78 (1H,d, J=1.9 Hz), 8.23 (1H, d, J=7.9 Hz). LC-MS (ESI) m/z 389 [M+H]⁺.

Preparative HPLC was performed at the conditions described below.

Column: Waters SunFire Column C18 (30×50 mm S-5 μm)

Column temp: 25° C.

Mobile phase: (A) 0.1% TFA in distilled water, (B) 0.1% TFA inacetonitrile

Gradient: 0 min (A/B=90/10)→1 min (A/B=90/10)→4.75 min (A/B=0/100)→7.40min (A/B=0/100)→7.41 min (A/B=90/10)→8.50 min (A/B=90/10)

Flow rate: 70 mL/min

Detector: UV 220 nm

Example 1573-[1-(2-methylpropyl)-1H-pyrazol-5-yl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one(300 mg, 0.85 mmol) in 20 mL of methanol, 2-methylpropylhydrazine (300mg, 3.39 mmol) was added, the resulting mixture was refluxed for 4hours, then concentrated. The residue was dissolved in dichloromethane(20 mL), washed with 1 M acetic acid aqueous solution and brine, driedover anhydrous Na₂SO₄, and concentrated under reduced pressure. Theresidue was purified by prep-HPLC to give the title compound (48 mg, 15%yield) as a yellow solid: ¹H NMR (400 MHz, CDCl₃): δ 0.83 (6H, d, J=6.8Hz), 2.17-2.25 (1H, m), 3.25-3.27 (4H, m), 3.89-3.92 (4H, m), 4.34 (2H,d, J=7.6 Hz), 6.72 (1H, d, J=8.0 Hz), 7.00-7.04 (2H, m), 7.33 (1H, d,J=2.4 Hz), 7.45-7.49 (2H, m), 7.59 (1H, d, J=2.0 Hz), 8.15 (1H, d, J=7.6Hz); LCMS (mobile phase: from 90% water and 10% CH3CN to 5% water and95% CH3CN in 6 min, finally under these conditions for 0.5 min.) purityis >95%, Rt=3.396 min; MS Calcd.: 379, MS Found: 380 [M+H]⁺.

Example 1583-[1-(2-Hydroxyethyl)-1H-pyrazol-5-yl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one(476 mg, 1.34 mmol) in 20 mL of methanol, 2-hydroxyethylhydrazine (414mg, 5.36 mmol) was added, the resulting mixture was refluxed for 4hours, and then concentrated. The residue was dissolved indichloromethane (20 mL), washed with 1 M acetic acid aqueous solutionand brine, dried over anhydrous Na₂SO₄, and concentrated under reducedpressure. The residue was purified by prep-HPLC to give the titlecompound (36 mg, 7.3% yield) as a yellow solid: ¹H NMR (400 MHz, CDCl₃):δ 3.20-3.22 (4H, m), 3.87-3.89 (4H, m), 4.03-4.05 (2H, m), 4.33-4.36(2H, m), 6.69 (1H, d, J=7.6 Hz), 6.98 (2H, dd, J=6.8, 2.0 Hz), 7.34 (1H,d, J=2.4 Hz), 7.51-7.53 (3H, m), 8.14 (1H, d, J=7.6 Hz); LCMS (mobilephase: from 95% water and 5% CH3CN to 5% water and 95% CH3CN in 6 min,finally under these conditions for 0.5 min.) purity is >95%, Rt=2.770min; MS Calcd.: 367, MS Found: 368 [M+H]⁺.

Example 1593-[1-(2,2-Dimethylpropyl)-1H-pyrazol-5-yl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one(300 mg, 0.85 mmol) in 20 mL of methanol, 2,2-dimethylpropylhydrazine(346 mg, 3.39 mmol) was added, the resulting mixture was refluxed for 4hours, and then concentrated. The residue was dissolved indichloromethane (20 mL), washed with 1 M acetic acid aqueous solutionand brine, dried over anhydrous Na₂SO₄, and concentrated under reducedpressure. The residue was purified by prep-HPLC to give the titlecompound (75 mg, 22% yield) as a yellow solid: ¹H NMR (400 MHz, CDCl₃):δ 0.83 (9H, s), 3.22-3.25 (4H, m), 3.88-3.90 (4H, m), 4.41 (2H, s), 6.70(1H, d, J=7.6 Hz), 7.00 (2H, d, J=9.2 Hz), 7.08 (1H, d, J=2.0 Hz), 7.45(2H, d, J=9.2 Hz), 7.58 (1H, d, J=2.0 Hz), 8.14 (1H, d, J=8.0 Hz); LCMS(mobile phase: from 70% water and 30% CH3CN to 5% water and 95% CH3CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=2.656 min; MS Calcd.: 393, MS Found: 394 (M⁺+H).

Example 1603-(1-Cyclopentyl-1H-pyrazol-5-yl)-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

To a solution of3-[3-(dimethylamino)prop-2-enoyl]-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one(300 mg, 0.85 mmol) in 20 mL of methanol, cyclopentylhydrazine (340 mg,3.39 mmol) was added, the resulting mixture was refluxed for 4 hours,and then concentrated. The residue was dissolved in dichloromethane (20mL), washed with 1 M acetic acid aqueous solution and brine, dried overanhydrous Na₂SO₄, and concentrated under reduced pressure. The residuewas purified by prep-HPLC to give the title compound (30 mg, 9% yield)as a brown solid: ¹H NMR (400 MHz, CDCl₃): δ 1.46-1.69 (5H, m),1.92-1.96 (1H, m), 2.04-2.09 (1H, m), 2.14-2.19 (1H, m), 3.22-3.25 (4H,m), 3.87-3.90 (4H, m), 5.10 (1H, quintet, J=3.6 Hz), 6.71 (1H, d, J=8.0Hz), 6.98-7.01 (2H, m), 7.04 (1H, d, J=1.6 Hz), 7.44-7.47 (2H, m), 7.60(1H, d, J=2.0 Hz), 8.16 (1H, d, J=7.6 Hz); LCMS (mobile phase: from 90%water and 10% CH3CN to 5% water and 95% CH3CN in 6 min, finally underthese conditions for 0.5 min.) purity is >95%, Rt=3.196 min; MS Calcd.:391, MS Found: 392 [M+H]⁺.

Example 1613-(1-Cyclohexyl-1H-pyrazol-5-yl)-1-(4-morpholin-4-ylphenyl)pyridazin-4(1H)-one

3-[(4-Morpholin-4-ylphenyl)hydrazono]pentane-2,4-dione (500 mg, 1.73mmol) was dissolved in 10 mL of N,N-dimethylformamide dimethyl acetal,and the mixture was refluxed for 4 hours, then concentrated underreduced pressure.

To a solution of the residue in 20 mL of methanol, cyclohexylhydrazine(790 mg, 6.92 mmol) was added, and the resulting mixture was refluxedfor 4 hours, then concentrated. The residue was dissolved indichloromethane (20 mL), washed with 1 M acetic acid aqueous solutionand brine, dried over anhydrous Na₂SO₄, and concentrated under reducedpressure. The residue was purified by prep-HPLC to give the titlecompound (50 mg, 7.1% yield) as a yellow solid: ¹H NMR (400 MHz, CDCl₃):δ 1.21-1.35 (3H, m), 1.63-1.69 (1H, m), 1.85-1.87 (2H, m), 2.00-2.06(4H, m), 3.21-3.25 (4H, m), 3.87-3.90 (4H, m), 4.58-4.65 (1H, m), 6.70(1H, dd, J=1.6, 8.0 Hz), 6.96-7.02 (2H, m), 7.12 (1H, d, J=1.6 Hz),7.45-7.50 (2H, m), 7.59-7.62 (1H, m), 8.19 (1H, d, J=8.0 Hz); LCMS(mobile phase: from 80% water and 20% CH3CN to 5% water and 95% CH3CN in6 min, finally under these conditions for 0.5 min.) purity is >95%,Rt=3.318 min; MS Calcd.: 405, MS Found: 406 [M+H]⁺.

Example 1621-(2-Fluoro-5-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-(2-fluoro-5-iodophenyl)-5-methoxypyridazin-4(1H)-one (3.88 g,10.0 mmol) in N,N-dimethylformamide dimethyl acetal (38.8 mL) was heatedto reflux for 3 h. The mixture was concentrated in vacuo. To the residuewere added AcOH (38.8 mL) and phenylhydrazine (1.97 mL, 20.0 mmol). Themixture was heated to reflux for 5 h. The mixture was concentrated invacuo, diluted with 1 M HCl aqueous solution, extracted with AcOEt,washed with saturated NaHCO₃ aqueous solution, dried over Na₂SO₄,filtered, concentrated in vacuo, purified by column chromatography onbasic silica gel (hexane/AcOEt=50/50 to 0/100) and triturated withAcOEt/hexane to yield the title compound (2.95 g, 60% yield) as a yellowsolid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 3.77 (3H, s), 6.99 (1H, d, J=1.5Hz), 7.23-7.50 (7H, m), 7.79 (1H, d, J=1.9 Hz), 7.84 (1H, ddd, J=8.7,4.5, 2.3 Hz), 8.49 (1H, d, J=2.6 Hz).

Example 1633-[1-(2-Fluorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one

A suspension of3-acetyl-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one(197 mg, 0.600 mmol) in N,N-dimethylformamide dimethyl acetal (2.0 mL)was stirred at 100° C. for 1 h. The reaction mixture was concentrated invacuo. To the residue were added AcOH (2.0 mL) and2-fluorophenylhydrazine (151 mg, 1.20 mmol). The mixture was stirred at100° C. for 1 h. After solvent evaporated, the residue was diluted withsaturated NaHCO₃ aqueous solution (25 mL) and extracted with AcOEt (25mL×3). The combined organic phase was washed with brine (40 mL), driedwith MgSO₄, and evaporated. The residue was crystallized from AcOEt togive a coarse solid, which was recrystallized from EtOH/hexane to givethe title compound (125 mg, 47% yield) as a white solid: mp 202-206° C.;¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.79 (3H, s), 6.64 (1H, d, J=1.9 Hz),6.96 (1H, t, J=8.5 Hz), 7.23-7.33 (3H, m), 7.41-7.53 (2H, m), 7.71 (1H,d, J=9.1 Hz), 7.84 (2H, dd, J=4.0, 1.7 Hz), 7.94 (1H, dd, J=12.3, 2.5Hz), 8.48 (1H, d, J=1.9 Hz), 8.65 (1H, d, J=2.6 Hz). LC-MS (ESI) m/z 447[M+H]⁺. Anal. Calcd for C₂₃H₁₆F₂N₆O₂.0.4H₂O: C, 60.90; H, 3.73; N,18.53. Found: C, 60.68; H, 3.69; N, 18.39.

Example 1643-[1-(3-Chlorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one

A suspension of3-acetyl-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one(393 mg, 1.20 mmol) in N,N-dimethylformamide dimethyl acetal (4.0 mL)was stirred at 100° C. for 1 h. The reaction mixture was concentrated invacuo. To the residue were added AcOH (4 mL) and 3-chlorophenylhydrazinehydrochloride (429 mg, 2.40 mmol). The mixture was stirred at 100° C.for 1 h. After solvent evaporated, the residue was diluted withsaturated NaHCO₃ aqueous solution (25 mL) and extracted with AcOEt (25mL×3). The combined organic phase was washed with brine (40 mL), driedwith MgSO₄, and evaporated. The residue was crystallized from AcOEt togive a coarse solid, which was recrystallized from EtOH/hexane to givethe title compound (242 mg, 44% yield) as an orange solid: mp 186-190°C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.80 (3H, s), 6.64 (1H, d, J=1.9Hz), 7.05 (1H, d, J=1.9 Hz), 7.27-7.34 (1H, m), 7.44 (3H, dd, J=16.6,10.2 Hz), 7.34-7.52 (1H, m), 7.84 (3H, dd, J=3.6, 1.7 Hz), 8.00 (1H, dd,J=12.3, 2.1 Hz), 8.56 (1H, d, J=1.9 Hz), 8.67 (1H, d, J=2.6 Hz): LC-MS(ESI) m/z 463 [M+H]⁺. Anal. Calcd for C₂₃H₁₆ClFN₆O₂.0.03H₂O: C, 59.61;H, 3.49; N, 18.14. Found: C, 59.32; H, 3.50; N, 17.92.

Example 1651-[4-(3-tert-Butyl-2-oxoimidazolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(488 mg, 1.0 mmol), 1-tert-butylimidazolidin-2-one (171 mg, 1.2 mmol),CuI (19 mg, 0.1 mmol), trans-1,2-diaminocyclohexane (0.024 mL, 0.2mmol), and K₃PO₄ (425 mg, 2.0 mmol) in toluene (5 mL) was stirred at 80°C. for 24 h under N₂ atmosphere. After cooling to room temperature, thereaction mixture was purified by silica gel column chromatographyeluting with hexane/AcOEt (1/1), AcOEt only and then AcOEt/MeOH (10/1)and recrystallized from AcOEt to give the title compound (198 mg, 39%yield) as a white solid: mp 238-239° C.; ¹H NMR (300 MHz, DMSO-d₆): δppm 1.36 (9H, s), 3.29 (3H, s), 3.44-3.59 (2H, m), 3.64-3.76 (2H, m),6.92-7.03 (2H, m), 7.23-7.51 (6H, m), 7.70 (1H, dd, J=14.1, 2.4 Hz),7.78 (1H, d, J=1.9 Hz), 8.43 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 503[M+H]⁺. Anal. Calcd for C₂₇H₂₇FN₆O₃: C, 64.53; H, 5.42; N, 16.72. Found:C, 64.31; H, 5.38; N, 16.58.

Example 1661-[2-Fluoro-4-(2-oxoimidazolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[4-(3-tert-butyl-2-oxoimidazolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(503 mg, 1.0 mmol) in trifluoroacetic acid (3.0 mL) was stirred at 80°C. for 1 h. After cooling to room temperature, the reaction mixture wasevaporated. The residue was recrystallized from AcOEt/MeOH to give thetitle compound (334 mg, 75% yield) as a pale yellow solid: mp 259-260°C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.40-3.50 (2H, m), 3.77 (3H, s),3.82-3.93 (2H, m), 6.95 (1H, d, J=2.3 Hz), 7.01 (1H, t, J=9.0 Hz),7.23-7.49 (7H, m), 7.73 (1H, dd, J=14.1, 2.4 Hz), 7.78 (1H, d, J=1.9Hz), 8.44 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 447 [M+H]⁺. Anal. Calcd forC₂₃H₁₉FN₆O₃.0.75H₂O: C, 60.06; H, 4.49; N, 18.27. Found: C, 60.05; H,4.26; N, 18.16.

Example 1671-{4-[3-(Difluoromethyl)-2-oxoimidazolidin-1-yl]-2-fluorophenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[2-fluoro-4-(2-oxoimidazolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(100 mg, 0.22 mmol), sodium chlorodifluoroacetate (40 mg, 0.26 mmol),and 18-crown-6 (12 mg, 0.044 mmol) in acetonitrile (10 mL) was stirredat 90° C. for 20 h. After cooling to room temperature, to the reactionmixture was added silica gel. This mixture was evaporated, and purifiedby silica gel column chromatography eluting with AcOEt/MeOH (1/0 to10/1) to give the title compound (2.5 mg, 2.3% yield) as a pale yellowpowder: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 1.11-1.40 (4H, m), 3.61-3.86(4H, m), 6.96 (1H, d, J=1.9 Hz), 7.01-7.15 (1H, m), 7.16-7.50 (6H, m),7.71 (1H, dd, J=13.6, 2.3 Hz), 7.79 (1H, d, J=2.3 Hz), 8.47 (1H, d,J=1.9 Hz). LC-MS (ESI) m/z 497 [M+H]⁺.

Example 1681-[3-(3,6-Dihydro-2H-pyran-4-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(441 mg, 1.0 mmol),4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,6-dihydro-2H-pyran(231 mg, 1.1 mmol), Pd(PPh₃)₄(57.8 mg, 0.05 mmol) and Na₂CO₃ (233 mg,2.2 mmol) in DME (8.8 mL) and water (2.2 mL) was heated to reflux for 15h under N₂. The mixture was diluted with NaHCO₃ aqueous solution,extracted with AcOEt, dried over Na₂SO₄, filtered, concentrated invacuo, purified by column chromatography on basic silica gel(hexane/AcOEt=50/50 to 0/100) and recrystallized with EtOH/hexane toyield the title compound (380 mg, 85% yield) as a white solid: mp138-141° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 2.42 (2H, brs), 3.74-3.89(5H, m), 4.21-4.29 (2H, m), 6.15 (1H, brs), 6.92-7.10 (2H, m), 7.17-7.59(7H, m), 7.78 (1H, d, J=1.9 Hz), 8.52 (1H, s). Anal. Calcd forC₂₅H₂₁FN₄O₃: C, 67.56; H, 4.76; N, 12.61. Found: C, 67.42; H, 4.83; N,12.44.

Example 1691-[2-Fluoro-3-(tetrahydro-2H-pyran-4-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[3-(3,6-dihydro-2H-pyran-4-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(190 mg, 0.427 mmol) and Pd/C (10% Pd, 50% wet, 19 mg) in MeOH (10 mL)was stirred at room temperature for 16 h under H₂. The mixture wasfiltered through a pad of Celite, concentrated in vacuo, purified bycolumn chromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100)and recrystallized with EtOH/hexane to yield the title compound (152 mg,79% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δ ppm1.60-1.85 (4H, m), 3.39-3.56 (3H, m), 3.77 (3H, s), 3.91-4.04 (2H, m),6.92-7.04 (2H, m), 7.21 (1H, t, J=8.1 Hz), 7.27-7.54 (6H, m), 7.78 (1H,d, J=1.9 Hz), 8.49 (1H, d, J=1.9 Hz).

Example 1701-(2-Fluoro-3-morpholin-4-ylphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(221 mg, 0.5 mmol), morpholine (0.0525 mL, 0.6 mmol), NaOt-Bu (67.3 mg,0.7 mmol), Xantphos (46.3 mg, 0.08 mmol) and Pd₂(dba)₃ (18.3 mg, 0.02mmol) in 1,4-dioxane (2.5 mL) was heated to 90° C. for 18 h under Ar.The mixture was diluted with NaHCO₃ aqueous solution, extracted withAcOEt, dried over Na₂SO₄, filtered, concentrated in vacuo, purified bycolumn chromatography on basic silica gel (hexane/AcOEt=50/50 to 0/100)and recrystallized with AcOEt/hexane and EtOH/hexane to yield the titlecompound (139 mg, 59% yield) as a pale yellow solid: mp 187-189° C. ¹HNMR (DMSO-d₆, 300 MHz): δ ppm 2.97-3.08 (4H, m), 3.70-3.80 (7H, m),6.61-6.72 (1H, m), 6.96 (1H, d, J=1.5 Hz), 7.06-7.17 (2H, m), 7.26-7.47(5H, m), 7.78 (1H, d, J=1.9 Hz), 8.50 (1H, d, J=1.9 Hz). Anal. Calcd forC₂₄H₂₂FN₅O₃: C, 64.42; H, 4.96; N, 15.65. Found: C, 64.47; H, 4.99; N,15.55.

Example 1711-[3-(3,3-Difluoroazetidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H-one

A mixture of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(177 mg, 0.4 mmol), 3,3-difluoroazetidine hydrochloride (62.2 mg, 0.48mmol), NaOt-Bu (99.9 mg, 1.04 mmol), Xantphos (99.9 mg, 0.173 mmol) andPd₂(dba)₃ (39.7 mg, 0.043 mmol) in 1,4-dioxane (2 mL) was heated to 90°C. for 16 h under N₂. The mixture was diluted with saturated NaHCO₃aqueous solution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo and purified by column chromatography on basicsilica gel (hexane/AcOEt=50/50 to 0/100) to yield the title compound(58.8 mg, 32% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz):δ ppm 3.77 (3H, s), 4.42 (4H, t, J=12.6 Hz), 6.43-6.82 (1H, m),6.90-7.49 (8H, m), 7.79 (1H, s), 8.39-8.60 (1H, m).

Example 1721-[3-(3,3-Difluoropyrrolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(221 mg, 0.5 mmol), 3,3-difluoropyrrolidine hydrochloride (86.1 mg, 0.6mmol), NaOt-Bu (125 mg, 1.3 mmol), Xantphos (46.3 mg, 0.08 mmol) andPd₂(dba)₃ (18.3 mg, 0.02 mmol) in 1,4-dioxane (2.5 mL) was heated to 90°C. for 24 h under N₂. The mixture was diluted with saturated NaHCO₃aqueous solution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo and purified by column chromatography on basicsilica gel (hexane/AcOEt=50/50 to 0/100) to yield the title compound(119 mg, 51% yield) as a pale yellow solid: ¹H NMR (DMSO-d₆, 300 MHz): δppm 2.42-2.50 (2H, m), 3.56 (2H, t, J=7.4 Hz), 3.71-3.88 (5H, m),6.43-6.54 (1H, m), 6.84-7.13 (3H, m), 7.27-7.49 (5H, m), 7.78 (1H, d,J=1.9 Hz), 8.47 (1H, d, J=2.3 Hz). Anal. Calcd for C₂₄H₂₀F₃N₅O₂.0.2H₂O:C, 61.20; H, 4.37; N, 14.87. Found: C, 61.36; H, 4.45; N, 14.56.

Example 1735-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-pyridin-3-ylpyridazin-4(1H)-one

A mixture of 3-acetyl-5-methoxy-1-pyridin-3-ylpyridazin-4(1H)-one (0.21g, 0.86 mmol) in N,N-dimethylformamide dimethyl acetal (10 mL, 75 mmol)was heated to reflux. MeOH (10 mL) was added to the mixture. Afterrefluxing for 2 h, the mixture was concentrated under reduced pressure.

A solution of the residue and phenylhydrazine (0.17 mL, 1.7 mmol) inAcOH (10 mL) was refluxed for 3 h. After stirring at room temperatureovernight, the mixture was concentrated under reduced pressure. Theresidue was diluted with AcOEt, and washed with saturated NaHCO₃ aqueoussolution and brine. The organic layer was dried over MgSO₄, filtered andconcentrated under reduced pressure. The residue was chromatographed onbasic silica gel (30/70-100/0 AcOEt/hexane) to give brown crystals. Thecrystals were recrystallized from 2-propanolheptane to give the titlecompound (70 mg, 24% yield) as beige crystals: mp 210-212° C.; ¹H NMR(300 MHz, DMSO-d₆): δ ppm 3.88 (3H, s), 7.16 (1H, d, J=1.9 Hz),7.35-7.50 (6H, m), 7.54-7.59 (1H, m), 7.81 (1H, d, J=1.9 Hz), 8.46 (1H,d, J=2.6 Hz), 8.54 (1H, dd, J=4.7, 1.3 Hz), 8.65 (1H, s). LC-MS (ESI)m/z 346 [M+H]⁺. Anal. Calcd. for C₁₉H₁₅N₅O₂: C, 66.08; H, 4.38; N,20.28. Found: C, 65.85; H, 4.34; N, 20.11.

Example 1741-{2-Fluoro-3-[3-(trifluoromethyl)pyrrolidin-1-yl]phenyl}-5-methoxy-3-(1-phenyl1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(300 mg, 0.68 mmol), 3-(trifluoromethyl)pyrrolidine hydrochloride (143mg, 0.82 mmol), NaOt-Bu (170 mg, 1.8 mmol), Xantphos (31 mg, 0.054 mmol)and Pd₂(dba)₃ (12 mg, 0.014 mmol) in 1,4-dioxane (4 mL) was heated at90° C. for 14 h under Ar. The mixture was extracted with AcOEt, driedover Na₂SO₄, filtered, concentrated in vacuo and purified by columnchromatography on basic silica gel (hexane/AcOEt=10/90 to 0/100) toyield the title compound (131 mg, 39% yield) as a white amorphous solid:¹H NMR (300 MHz, CDCl₃): δ ppm 2.09-2.40 (2H, m), 3.05 (1H, s),3.38-3.75 (4H, m), 3.83-3.99 (3H, m), 5.88-6.07 (1H, m), 6.65 (1H, td,J=8.3, 1.5 Hz), 6.80-6.95 (1H, m), 7.22 (1H, d, J=2.3 Hz), 7.30-7.49(5H, m), 7.72 (1H, d, J=2.6 Hz), 7.74-7.80 (1H, m); MS Calcd.: 499; MSFound: 500 [M+H]⁺.

Example 1751-{2-Fluoro-4-[3-(trifluoromethyl)pyrrolidin-1-yl]phenyl}-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(300 mg, 0.61 mmol), 3-(trifluoromethyl)pyrrolidine hydrochloride (130mg, 0.74 mmol), NaOt-Bu (154 mg, 1.6 mmol), Xantphos (28 mg, 0.049 mmol)and Pd₂(dba)₃ (11 mg, 0.012 mmol) in 1,4-dioxane (4 mL) was heated to90° C. for 12 h under Ar. The mixture was extracted with AcOEt, driedover Na₂SO₄, filtered, concentrated in vacuo and purified by columnchromatography on basic silica gel (hexane/AcOEt=10/90 to 0/100) toyield the title compound (138 mg, 45% yield) as a pale green solid: ¹HNMR (300 MHz, CDCl₃): δ ppm 2.17-2.42 (2H, m), 3.01-3.21 (1H, m),3.30-3.63 (4H, m), 3.89 (3H, s), 6.11 (1H, dd, J=8.9, 2.4 Hz), 6.20-6.37(2H, m), 7.24 (1H, d, J=1.9 Hz), 7.33-7.47 (5H, m), 7.71 (1H, d, J=2.3Hz), 7.77 (1H, d, J=1.9 Hz); MS Calcd.: 499; MS Found: 500 [M+H]⁺.

Example 1761-[2-Fluoro-3-(3,3,4,4-tetrafluoropyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(221 mg, 0.500 mmol), 3,3,4,4-tetrafluoropyrrolidine hydrochloride (108mg, 0.600 mmol), sodium tert-butoxide (125 mg, 1.300 mmol), Xantphos (23mg, 0.040 mmol), and tris(dibenzylideneacetone)dipalladium(0) (9 mg,0.010 mmol) in 1,4-dioxane (2.5 mL) was stirred at 90° C. under Aratmosphere. The reaction mixture was poured into 5% NaHCO₃ aqueoussolution (20 mL) and extracted with AcOEt (20 mL×3). The combinedorganic phase was washed with brine (40 mL), dried with MgSO₄, andevaporated. The residue was purified by silica gel column chromatography(AcOEt/hexane=60%-100%) to give the title compound (95.4 mg, 38% yield)as an amorphous solid: ¹H NMR (300 MHz, CDCl₃): δ ppm 3.84-3.96 (7H, m),6.11 (1H, t, J=7.5 Hz), 6.60 (1H, td, J=8.3, 1.5 Hz), 6.90-6.98 (1H, m),7.25 (1H, d, J=1.9 Hz), 7.33-7.41 (5H, m), 7.70 (1H, d, J=2.6 Hz), 7.78(1H, d, J=1.9 Hz). LC-MS (ESI) m/z 504 [M+H]⁺.

Example 1771-(2-Fluoro-3-pyridin-3-ylphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A solution of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(177 mg, 0.400 mmol), 3-pyridineboronic acid (54.1 mg, 0.440 mmol),tetrakis(triphenylphosphine)palladium(0) (23 mg, 0.020 mmol) and Na₂CO₃(93 mg, 0.88 mmol) in DME (3.6 mL) and water (0.9 mL) was stirred at 85°C. for 5 h under Ar atmosphere. The mixture was poured into 5% NaHCO₃aqueous solution (20 mL) and extracted with AcOEt (20 mL×3). Thecombined organic phase was washed with brine (30 mL), dried with MgSO₄,and evaporated. The residue was purified by basic silica gel columnchromatography (MeOH/AcOEt=0%-10%) and crystallized from AcOEt to givethe title compound (84.8 mg, 48% yield) as a colorless solid: mp147-153° C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.78 (3H, s), 7.01 (1H, d,J=1.9 Hz), 7.04-7.17 (1H, m), 7.28-7.51 (6H, m), 7.56 (1H, dd, J=7.7,5.1 Hz), 7.63-7.75 (1H, m), 7.79 (1H, d, J=1.9 Hz), 8.03 (1H, dd, J=7.9,1.9 Hz), 8.58-8.68 (2H, m), 8.81 (1H, s). LC-MS (ESI) m/z 440 [M+H]⁺.Anal. Calcd for C₂₅H₁₈FN₅O₂: C, 68.33; H, 4.13; N, 15.94. Found: C,68.04; H, 4.03; N, 15.80.

Example 1781-[2-fluoro-4-(3-methyl-2-oxoimidazolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-[2-fluoro-4-(2-oxoimidazolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(40 mg, 0.09 mmol), iodomethane (0.02 mL, 0.36 mmol), and sodium hydride(60% in oil) (7.0 mg, 0.18 mmol) in DMF (4.0 mL) was stirred at 0° C.for 2 h. The reaction mixture was quenched with H₂O, and extracted withAcOEt. The organic layer was dried over MgSO₄, and concentrated underreduced pressure. The residue was recrystallized from ^(i)Pr₂O/AcOEt togive the title compound (24 mg, 59% yield) as a white solid: mp 208-209°C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 2.79 (3H, s), 3.42-3.58 (2H, m),3.77 (3H, s), 3.78-3.86 (2H, m), 6.95 (1H, d, J=1.9 Hz), 7.01 (1H, t,J=9.0 Hz), 7.22-7.51 (6H, m), 7.73 (1H, dd, J=14.1, 2.4 Hz), 7.78 (1H,d, J=1.9 Hz), 8.44 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 461 [M+H]⁺. Anal.Calcd for C₂₄H₂₁FN₆O₃.0.75H₂O: C, 60.06; H, 4.49; N, 18.27. Found: C,60.05; H, 4.26; N, 18.16.

Example 1791-[4-(2,5-Dihydro-1H-pyrrol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 3-pyrroline (0.046 mL, 0.6 mmol), Pd₂(dba)₃ (18.3mg, 0.02 mmol), Xantphos (46.3 mg, 0.08 mmol), and NaOtBu (67.3 mg, 0.7mmol) in 1,4-dioxane (2.5 mL) was stirred for 2 h at 90° C. under Aratmosphere. The reaction mixture was poured into water and extractedwith AcOEt. The extract was washed with brine, dried over MgSO₄, andconcentrated under reduced pressure. The residue was purified by basicsilica gel column chromatography eluting with hexane/THF (1/2) andrecrystallized from MeOH/H₂O to give the title compound (109 mg, 51%yield) as a yellow solid: mp 204-207° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm3.89 (3H, s), 4.09 (4H, s), 5.97 (2H, t, J=4.1 Hz), 6.07 (1H, dd, J=2.6,9.0 Hz), 6.19 (1H, dd, J=2.6, 14.3 Hz), 6.32 (1H, t, J=9.0 Hz), 7.24(1H, d, J=1.9 Hz), 7.33-7.45 (5H, m), 7.72 (1H, d, J=2.3 Hz), 7.77 (1H,d, J=1.9 Hz). LC-MS (ESI) m/z 430 [M+H]⁺. Anal. Calcd for C₂₄H₂₀FN₅O₂:C, 67.12; H, 4.69; N, 16.31. Found: C, 67.03; H, 4.76; N, 16.16.

Example 1801-[4-(4-Chloro-1H-pyrazol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(488 mg, 1.0 mmol), 4-chloro-1H-pyrazole (103 mg, 1.0 mmol), Cu₂O (14.3mg, 0.1 mmol), salicylaldoxime (54.9 mg, 0.4 mmol), and Cs₂CO₃ (652 mg,2.0 mmol) in CH₃CN (10 mL) was refluxed overnight under Ar atmosphere.After cooling to room temperature, the reaction mixture was poured intowater and extracted with AcOEt. The extract was washed with brine, driedover MgSO₄, and concentrated under reduced pressure. The residue wassubjected to basic silica gel column chromatography eluting with AcOEtfollowed by purification by preparative HPLC. Recrystallization fromMeOH/H₂O gave the title compound (68.1 mg, 15% yield) as a pale yellowpowder: mp 190-192° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.92 (3H, s),6.43 (1H, t, J=9.0 Hz), 7.23 (1H, ddd, J=1.1, 2.3, 9.0 Hz), 7.35 (1H, d,J=1.9 Hz), 7.36-7.48 (5H, m), 7.57 (1H, dd, J=2.6, 12.4 Hz), 7.68 (1H,s), 7.79 (1H, d, J=1.9 Hz), 7.82 (1H, d, J=2.3 Hz), 7.92 (1H, d, J=0.8Hz). LC-MS (ESI) m/z 463 [M+H]⁺. Anal. Calcd for C₂₃H₁₆ClFN₆O₂: C,59.68; H, 3.48; N, 18.16. Found: C, 59.81; H, 3.50; N, 18.14.

Preparative HPLC was performed at the conditions described below.

Column: CHIRALPAK AS CC001 (50 mm ID×500 mmL)

Column temp: 30° C.

Mobile phase: MeOH

Flow rate: 60 mL/min

Detector: UV 220 nm

Concentration: 111 mg/mL

Inject volume: 1 mL

Retention time: 18.8 min

Example 1811-[5-(3,3-Difluoroazetidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-5-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), 3,3-difluoroazetidine hydrochloride (77.7 mg, 0.6mmol), NaOtBu (125 mg, 1.3 mmol), Xantphos (46.3 mg, 0.08 mmol) andPd₂(dba)₃ (18.3 mg, 0.02 mmol) in 1,4-dioxane (2.5 mL) was heated to 90°C. for 13 h under Ar. The mixture was diluted with saturated NaHCO₃aqueous solution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and recrystallized with EtOH/hexane toyield the title compound (92 mg, 41% yield) as a white solid: ¹H NMR(DMSO-d₆, 300 MHz): δ ppm 3.77 (3H, s), 4.25 (4H, t, J=12.2 Hz), 6.48(1H, dd, J=6.4, 3.0 Hz), 6.63-6.72 (1H, m), 6.90 (1H, d, J=1.5 Hz),7.25-7.48 (6H, m), 7.79 (1H, d, J=1.9 Hz), 8.45 (1H, d, J=1.9 Hz). Anal.Calcd for C₂₃H₁₈F₃N₅O₂: C, 60.93; H, 4.00; N, 15.45. Found: C, 60.97; H,3.94; N, 15.47.

Example 1821-[2-Fluoro-5-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-5-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), pyrrolidin-2-one (0.0456 mL, 0.6 mmol), K₃PO₄ (212mg, 1.0 mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.1 mmol) and CuI(9.5 mg, 0.05 mmol) in 1,4-dioxane (2 mL) was heated to reflux for 13 hunder Ar. The mixture was diluted with saturated NaHCO₃ aqueoussolution, extracted with AcOEt, dried over Na₂SO₄, filtered,concentrated in vacuo, purified by column chromatography on basic silicagel (hexane/AcOEt=50/50 to 0/100) and recrystallized with AcOEt/hexaneto yield the title compound (126 mg, 57% yield) as a white solid: mp171-174° C. ¹H NMR (DMSO-d₆, 300 MHz): δ ppm 2.02-2.19 (2H, m),2.47-2.58 (2H, m), 3.69-3.87 (5H, m), 6.92 (1H, d, J=1.9 Hz), 7.22-7.58(7H, m), 7.74-7.89 (2H, m), 8.51 (1H, d, J=1.9 Hz). Anal. Calcd forC₂₄H₂₀FN₅O₃: C, 64.71; H, 4.53; N, 15.72. Found: C, 64.59; H, 4.45; N,15.67.

Example 1831-[2-Fluoro-5-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of1-(2-fluoro-5-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.5 mmol), pyrazole (34.0 mg, 0.5 mmol), 2-hydroxybenzaldehydeoxime (27.4 mg, 0.2 mmol), Cu₂O (7.2 mg, 0.05 mmol) and Cs₂CO₃ (326 mg,1.0 mmol) in acetonitrile (1 mL) was heated to reflux for 14 h under Ar.The mixture was diluted with saturated NaHCO₃ aqueous solution,extracted with AcOEt, dried over Na₂SO₄, filtered, concentrated invacuo, purified by column chromatography on basic silica gel(hexane/AcOEt=50/50 to 0/100) and on silica gel (hexane/AcOEt=50/50 to0/100) and recrystallized with AcOEt/hexane to yield the title compound(8.3 mg, 4% yield) as a white solid: mp 186-187° C. ¹H NMR (DMSO-d₆, 300MHz): δ ppm 3.78 (3H, s), 6.59-6.66 (1H, m), 6.95 (1H, d, J=1.9 Hz),7.17-7.27 (1H, m), 7.30-7.42 (4H, m), 7.56-7.67 (1H, m), 7.76-7.90 (3H,m), 7.93-8.02 (1H, m), 8.47 (1H, d, J=2.6 Hz), 8.59 (1H, d, J=1.9 Hz).Anal. Calcd for C₂₃H₁₇FN₆O₂: C, 64.48; H, 4.00; N, 19.62. Found: C,64.21; H, 4.08; N, 19.42.

Example 1841-[2-Fluoro-3-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(221 mg, 0.5 mmol), 2-pyrrolidinone (46 μL, 0.60 mmol),N,N′-dimethylethylenediamine (22 μL, 0.20 mmol), CuI (19 mg, 0.10 mmol),and K₃PO₄ (212 mg, 1.00 mmol) in 1,4-dioxane (2.0 mL) was stirred at 90°C. under Ar atmosphere. The reaction mixture was poured into 5% NaHCO₃aqueous solution (20 mL) and extracted with AcOEt (20 mL×3). Thecombined organic phase was washed with brine (40 mL), dried with MgSO₄,and evaporated. The residue was purified by basic silica gel columnchromatography (AcOEt/hexane=50%-100%) to give the title compound (89.4mg, 40% yield) as an amorphous solid: ¹H NMR (300 MHz, CDCl₃): δ ppm2.26 (2H, q, J=7.7 Hz), 2.59 (2H, t, J=8.1 Hz), 3.80 (2H, t, J=7.0 Hz),3.89 (3H, s), 6.36 (1H, dd, J=15.5, 1.9 Hz), 7.03 (1H, t, J=8.3 Hz),7.30 (1H, d, J=1.9 Hz), 7.34-7.49 (6H, m), 7.73-7.83 (2H, m). LC-MS(ESI) m/z 446 [M+H]⁺. Anal. Calcd for C₂₄H₂₀FN₅O₃.0.2H₂O: C, 64.19; H,4.58; N, 15.59. Found: C, 64.00; H, 4.51; N, 15.56.

Example 1851-[2-Fluoro-3-(2-oxopiperidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(3-bromo-2-fluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(221 mg, 0.500 mmol), 2-piperidone (59.5 mg, 0.600 mmol),N,N′-dimethylethylenediamine (0.022 mL, 0.200 mmol), CuI (19 mg, 0.10mmol) and K₃PO₄ (212 mg, 1.00 mmol) in 1,4-dioxane (2.0 mL) was stirredat 90° C. under Ar atmosphere. The reaction mixture was poured into 5%NaHCO₃ aqueous solution (20 mL) and extracted with AcOEt (20 mL×3). Thecombined organic phase was washed with brine (40 mL), dried with MgSO₄,and evaporated. The residue was purified by basic silica gel columnchromatography (AcOEt/hexane=50%-100%) to give the title compound (52.3mg, 23% yield) as an amorphous solid: ¹H NMR (300 MHz, CDCl₃): δ ppm1.97 (4H, t, J=3.4 Hz), 2.54-2.63 (2H, m), 3.56 (2H, brs), 3.88 (3H, s),6.36 (1H, dd, J=15.5, 1.9 Hz), 7.03 (1H, dd, J=16.2, 1.5 Hz), 7.22 (1H,dd, J=14.7, 1.9 Hz), 7.29 (1H, d, J=2.3 Hz), 7.35-7.44 (2H, m), 7.40(3H, d, J=4.5 Hz), 7.78 (1H, d, J=1.9 Hz), 7.82 (1H, d, J=2.6 Hz). LC-MS(ESI) m/z 460 [M+H]⁺. Anal. Calcd for C₂₅H₂₂FN₅O₃.0.5H₂O: C, 64.34; H,4.93; N, 15.00. Found: C, 64.12; H, 4.73; N, 15.13.

Example 1861-[2-Fluoro-4-(4-hydroxy-4-methylpiperidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.500 mmol), 4-methylpiperidin-4-ol hydrochloride (91 mg, 0.60mmol), sodium tert-butoxide (187 mg, 1.95 mmol), Xantphos (23 mg, 0.040mmol), and tris(dibenzylideneacetone)dipalladium(0) (9 mg, 0.010 mmol)in 1,4-dioxane (2.5 mL) was stirred at 90° C. under Ar atmosphere. Thereaction mixture was poured into 5% NaHCO₃ aqueous solution (20 mL) andextracted with AcOEt (20 mL×3). The combined organic phase was washedwith brine (40 mL), dried with MgSO₄, and evaporated. The residue waspurified by basic silica gel column chromatography (MeOH/AcOEt=0%-20%).The residue was recrystallized from AcOEt/hexane to give the titlecompound (76.2 mg, 32% yield) as a pale yellow solid: ¹H NMR (300 MHz,DMSO-d₆): δ ppm 1.14 (3H, s), 1.39-1.60 (4H, m), 3.20 (2H, ddd, J=13.2,8.7, 5.3 Hz), 3.40-3.52 (2H, m), 3.76 (3H, s), 4.36 (1H, s), 6.70 (1H,dd, J=9.0, 2.6 Hz), 6.91 (2H, d, J=1.9 Hz), 6.79-6.94 (1H, m), 7.32 (1H,d, J=1.9 Hz), 7.29 (1H, s), 7.35-7.47 (3H, m), 7.77 (1H, d, J=1.9 Hz),8.37 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 476 [M+H]⁺. Anal. Calcd forC₂₆H₂₆FN₅O₃: C, 65.67; H, 5.51; N, 14.73. Found: C, 65.53; H, 5.50; N,14.66.

Example 187 1-(4-Bromo-2,5-difluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-(4-bromo-2,5-difluorophenyl)-5-methoxypyridazin-4(1H)-one(3.57 g, 10 mmol) and N,N-dimethylformamide dimethyl acetal (16 mL) wasstirred at 100° C. for 5 h. After cooling to room temperature, thereaction mixture was concentrated under reduced pressure. The residuewas dissolved in AcOH (20 mL) and added phenylhydrazine (2.0 mL, 20mmol). This mixture was stirred at 130° C. for 3 h. After cooling toroom temperature, the reaction mixture was concentrated under reducedpressure. The residue was purified by silica gel column chromatographyeluting with hexane/AcOEt (1/0 to 0/1) and recrystallized from^(i)Pr₂O/AcOEt to give the title compound (1.05 g, 23% yield) as a paleyellow solid: mp 211-213° C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 3.77 (3H,s), 7.02 (1H, d, J=1.9 Hz), 7.09 (1H, dd, J=8.9, 6.6 Hz), 7.22-7.62 (5H,m), 7.80 (1H, d, J=1.9 Hz), 8.07 (1H, dd, J=10.2, 6.0 Hz), 8.49 (1H, d,J=2.3 Hz). LC-MS (ESI) m/z 460 [M+H]⁺. Anal. Calcd for C₂₀H₁₃BrF₂N₄O₂:C, 52.31; H, 2.85; N, 12.20. Found: C, 52.51; H, 2.95; N, 12.20.

Example 188 1-[2,5-Difluoro-4-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(4-bromo-2,5-difluorophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(200 mg, 0.44 mmol), pyrrolidin-2-one (0.040 mL, 0.53 mmol), CuI (17 mg,0.088 mmol), N,N′-dimethylethane-1,2-diamine (0.019 mL, 0.18 mmol), andK₃PO₄ (187 mg, 0.88 mmol) in 1,4-dioxane (4.0 mL) was stirred at 80° C.for 14 h under N₂ atmosphere. After cooling to rt, the reaction mixturewas purified by silica gel column chromatography eluting withhexane/AcOEt (1/0 to 0/1) then AcOEt/MeOH (10/1) and recrystallized fromAcOEt to give the title compound (12 mg, 6% yield) as a pale brownsolid: ¹H NMR (300 MHz, DMSO-d₆): δ ppm 2.06-2.23 (2H, m), 3.29 (3H, s),3.69-3.91 (4H, m), 7.27-7.42 (2H, m), 7.43-7.56 (2H, m), 7.78 (1H, dd,J=11.3, 6.4 Hz), 7.85-7.91 (2H, m), 7.95 (1H, dd, J=10.5, 7.2 Hz), 8.57(1H, d, J=2.3 Hz), 8.60 (1H, d, J=1.5 Hz). LC-MS (ESI) m/z 464 [M+H]⁺.

Example 1891-[4-(4,4-Dimethyl-2-oxopyrrolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.500 mmol), 4,4-dimethyl-2-pyrrolidinone (67.9 mg, 0.600mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.10 mmol), CuI (9.5 mg,0.050 mmol), and K₃PO₄ (212 mg, 1.00 mmol) in 1,4-dioxane (2.0 mL) wasstirred at 110° C. under Ar atmosphere. The reaction mixture was pouredinto 5% NaHCO₃ aqueous solution (20 mL) and extracted with AcOEt (20mL×3). The combined organic phase was washed with brine (40 mL), driedwith MgSO₄, and evaporated. The residue was purified by basic silica gelcolumn chromatography (AcOEt/hexane=50%-100%) and silica gel columnchromatography (AcOEt/hexane=50%-100%) to give the title compound (142.8mg, 60% yield): ¹H NMR (300 MHz, DMSO-d₆): δ ppm 1.16 (6H, s), 2.39-2.44(2H, m), 3.58-3.63 (2H, m), 3.77 (3H, s), 6.94-6.98 (1H, m), 6.98-7.08(1H, m), 7.29-7.35 (2H, m), 7.35-7.49 (4H, m), 7.68-7.88 (2H, m),8.37-8.55 (1H, m). LC-MS (ESI) m/z 474 [M+H]⁺. Anal. Calcd forC₂₆H₂₄FN₅O₃.0.2H₂O: C, 65.45; H, 5.16; N, 14.68. Found: C, 65.17; H,5.16; N, 14.55.

Example 1901-[4-(5,5-Dimethyl-2-oxo-1,3-oxazolidin-3-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(244 mg, 0.500 mmol), 5,5-dimethyl-1,3-oxazolidin-2-one (69.1 mg, 0.600mmol), trans-1,2-diaminocyclohexane (0.012 mL, 0.100 mmol), CuI (9.5 mg,0.050 mmol), and K₃PO₄ (212 mg, 1.00 mmol) in 1,4-dioxane (2.0 mL) wasstirred at 110° C. under Ar atmosphere. The reaction mixture was pouredinto 5% NaHCO₃ aqueous solution (20 mL) and extracted with AcOEt (20mL×3). The combined organic phase was washed with brine (40 mL), driedwith MgSO₄, and evaporated. The residue was purified by basic silica gelcolumn chromatography (MeOH/AcOEt=0%-10%) to give the title compound(157.4 mg, 66% yield): ¹H NMR (300 MHz, DMSO-d₆): δ ppm 1.49 (6H, s),3.78 (3H, s), 3.89 (2H, s), 6.97 (1H, d, J=1.9 Hz), 7.05 (1H, t, J=9.0Hz), 7.31 (1H, d, J=8.7 Hz), 7.31 (1H, t, J=1.7 Hz), 7.33 (1H, s),7.37-7.48 (3H, m), 7.68 (1H, dd, J=13.4, 2.5 Hz), 7.79 (1H, d, J=1.9Hz), 8.46 (1H, d, J=2.3 Hz). LC-MS (ESI) m/z 476 [M+H]⁺. Anal. Calcd forC₂₅H₂₂FN₅O₄: C, 63.15; H, 4.66; N, 14.73. Found: C, 63.09; H, 4.70; N,14.85.

Example 1916-{3-Fluoro-4-[5-methoxy-4-oxo-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-1(4H)-yl]phenyl}-4-oxa-6-azaspiro[2.4]heptan-5-one

A suspension of1-(2-fluoro-4-iodophenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one(0.24 g, 0.50 mmol), 4-oxa-6-azaspiro[2.4]heptan-5-one (0.068 g, 0.60mmol), trans-1,2-diaminocyclohexane (0.024 mL, 0.20 mmol), CuI (0.019 g,0.10 mmol), and K₃PO₄ (0.21 g, 1.0 mmol) in 1,4-dioxane (3 mL) wasstirred at 110° C. under Ar atmosphere for 2 h. The mixture was dilutedwith AcOEt and filtered through a basic-silica gel pad, and then thesilica gel was washed with AcOEt. The filtrate was concentrated underreduced pressure. The residue was chromatographed on basic silica gel(0/100-3/97 MeOH/AcOEt) to give white crystals. The crystals wererecrystallized from AcOEt/hexane to give the title compound (0.17 g, 72%yield) as a white solid: mp 200-201° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm0.85-0.92 (2H, m), 1.33-1.40 (2H, m), 3.90 (3H, s), 4.08 (2H, s), 6.39(1H, t, J=8.9 Hz), 6.96 (1H, ddd, J=8.9, 2.5, 1.4 Hz), 7.30 (1H, d,J=1.9 Hz), 7.35-7.45 (5H, m), 7.68 (1H, dd, J=13.7, 2.5 Hz), 7.77-7.79(2H, m). LC-MS (ESI) m/z 474 [M+H]⁺. Anal. Calcd. for C₂₅H₂₀FN₅O₄.H₂O:C, 62.94; H, 4.31; N, 14.68. Found: C, 62.83; H, 4.42; N, 14.77.

Example 1925-Methoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-5-methoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]pyridazin-4(1H)-one(1.50 g, 4.41 mmol), N,N-dimethylformamide dimethyl acetal (15 mL), andMeOH (15 mL) was refluxed for 3 h. After cooling to room temperature,the reaction mixture was concentrated under reduced pressure.

A solution of the residue and phenylhydrazine (0.868 mL, 8.82 mmol) inAcOH (15 mL) was refluxed for 2 h. After cooling to room temperature,the reaction mixture was poured into 1 M HCl aqueous solution andextracted with AcOEt. The extract was washed with 1 M NaOH aqueoussolution and brine, dried over MgSO₄, and concentrated under reducedpressure. The residue was purified by basic silica gel columnchromatography eluting with AcOEt and crystallized from hexane/AcOEt togive the title compound (0.921 g, 47% yield) as an off-white solid: mp133-135° C.; ¹H NMR (300 MHz, CDCl₃): δ ppm 3.90 (3H, s), 3.93 (3H, s),6.39 (1H, d, J=8.7 Hz), 6.52 (1H, dd, J=1.9, 2.6 Hz), 6.99 (1H, dd,J=2.3, 8.7 Hz), 7.26 (1H, d, J=1.9 Hz), 7.36-7.46 (5H, m), 7.49 (1H, d,J=2.3 Hz), 7.75 (1H, d, J=1.9 Hz), 7.77 (1H, d, J=1.9 Hz), 7.86 (1H, s),7.94 (1H, d, J=2.6 Hz). LC-MS (ESI) m/z 441 [M+H]⁺. Anal. Calcd forC₂₄H₂₀N₆O₃: C, 65.45; H, 4.58; N, 19.08. Found: C, 65.37; H, 4.65; N,18.88.

Example 1936-Methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one

To a solution6-hydroxy-3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one(0.23 g, 0.58 mmol) in MeOH (10 mL) was added dropwisetrimethylsilyldiazomethane (2 M solution in diethylether, 8.0 mL, 16.0mmol) at 0° C., and the mixture was stirred at 0° C. for 1 h. Themixture was concentrated under reduced pressure. The residue waspurified by silica gel column chromatography eluting with AcOEt/hexane(20/80-100/0) and recrystallized from AcOEt/hexane to give the titlecompound (0.023 g, 10% yield) as white crystals: mp 139-141° C.; ¹H NMR(300 MHz, CDCl₃): δ ppm 3.90 (3H, s), 6.14 (1H, s), 6.97-7.02 (1H, m),7.13 (1H, s), 7.22 (1H, d, J=1.9 Hz), 7.31-7.44 (6H, m), 7.56-7.61 (1H,m), 7.76 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 413 [M+H]⁺. Anal. Calcd forC₂₁H₁₅F₃N₄O₂: C, 61.17; H, 3.67; N, 13.59. Found: C, 61.19; H, 3.71; N,13.69.

Example 1941-(2,3-Difluoro-4-morpholin-4-ylphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-(2,3-difluoro-4-morpholin-4-ylphenyl)-5-methoxypyridazin-4(1H)-one(200 mg, 0.55 mmol) and N,N-dimethylformamide dimethyl acetal (2.0 mL)was stirred at 120° C. for 2.5 h. After cooling to room temperature, thereaction mixture was concentrated under reduced pressure. The residuewas dissolved in AcOH (2.0 mL) and phenylhydrazine (0.11 mL, 1.1 mmol)was added. This mixture was stirred at room temperature for 1 h, andthen the reaction mixture was concentrated under reduced pressure. Theresidue was purified by silica gel column chromatography eluting withAcOEt/MeOH (1/0 to 10/1) and recrystallized from ^(i)Pr₂O/AcOEt to givethe title compound (141 mg, 55% yield) as a yellow solid: mp 182-183°C.; ¹H NMR (300 MHz, DMSO-d₆): δ ppm 2.98-3.22 (4H, m), 3.62-3.87 (7H,m), 6.78-6.92 (2H, m), 6.95 (1H, d, J=1.9 Hz), 7.21-7.54 (5H, m), 7.78(1H, d, J=1.9 Hz), 8.48 (1H, d, J=1.9 Hz). LC-MS (ESI) m/z 466 [M+H]⁺.Anal. Calcd for C₂₄H₂₁F₂N₅O₃: C, 61.93; H, 4.55; N, 15.05. Found: C,61.90; H, 4.58; N, 14.87.

Example 1951-(2,5-Difluoro-4-morpholin-4-ylphenyl)-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one

A mixture of3-acetyl-1-(2,5-difluoro-4-morpholin-4-ylphenyl)-5-methoxypyridazin-4(1H)-one(340 mg, 0.93 mmol) and N,N-dimethylformamide dimethyl acetal (3.4 mL)was stirred at 120° C. for 2.5 h. After cooling to room temperature, thereaction mixture was concentrated under reduced pressure. The residuewas dissolved in AcOH (3.4 mL) and phenylhydrazine (0.18 mL, 1.9 mmol)was added. This mixture was stirred at room temperature for 1 h. Thereaction mixture was diluted with AcOEt, and washed with saturatedNaHCO₃ aqueous solution and brine. The organic layer was dried overMgSO₄, and concentrated under reduced pressure. The residue wasrecrystallized from AcOEt/MeOH to give the title compound (156 mg, 36%yield) as a pale orange solid: mp 211-212° C.; ¹H NMR (300 MHz,DMSO-d₆): δ ppm 2.99-3.15 (4H, m), 3.60-3.88 (7H, m), 6.85 (1H, dd,J=12.8, 7.2 Hz), 6.99 (1H, d, J=2.3 Hz), 7.09 (1H, dd, J=12.8, 7.6 Hz),7.24-7.50 (5H, m), 7.79 (1H, d, J=1.9 Hz), 8.43 (1H, d, J=2.3 Hz). LC-MS(ESI) m/z 466 [M+H]⁺. Anal. Calcd for C₂₄H₂₁F₂N₅O₃.0.5H₂O: C, 60.75; H,4.67; N, 14.76. Found: C, 60.98; H, 4.71; N, 14.63.

Test Example 1

PDE Enzyme Inhibition

Human PDE10A enzyme was generated from Sf9 or COS-7 cells transfectedwith the full-length gene. Cloned enzyme was extracted from homogenizedcell pellets. The extracted enzyme from sf9 cells was partially purifiedusing His-tag affinity column. The enzyme was stored at −70° C. untiluse. PDE activity was measured using a SPA (Scintillation ProximityAssay) (GE Healthcare). To evaluate the inhibitory activity, 10 μL ofserial diluted compounds were incubated with 20 μL of PDE enzyme inassay buffer (50 mM HEPES-NaOH, 8.3 mM MgCl₂, 1.7 mM EGTA, 0.1% BSA (pH7.4)) for 30 min. at room temperature. Final concentration of DMSO inthe assay was 1 percent as compounds were tested in duplicate in 96-wellhalf-area plates (Corning). To start the reaction, 10 μL of substrate[3H] cGMP (25 or 50 nM; enclosed in SPA kits from GE Healthcare orpurchased from PerkinElmer, respectively) was added for a final assayvolume of 40 μL. After 60 min incubation at room temperature, yttriumSPA beads containing Zinc sulphate were added (20 μL at 6 mg/mL) toterminate the PDE reaction. After being settled for 60 min., assayplates were counted in a scintillation counter (PerkinElmer) to allowcalculation of inhibition rate and IC₅₀. Inhibition rate was calculatedon the basis of 0% control wells with DMSO and 100% control wellswithout enzyme. The results are shown in Tables 1 and 2.

TABLE 1 IC₅₀ A: less than 10 nM Percent inhibition Example No. B: 10-200nM (1 μM) 10 B 98 13 B 96 15 B 97 16 B 97 17 B 97 23 A 102 26 B 97 30 B87 (at 0.1 μM) 32 B 89 36 A 90 (at 0.1 μM) 39 A 98 46 B 97 48 A 100 49 A98 52 A 99 54 A 100 57 A 101 59 B 96 64 B 94

TABLE 2 IC₅₀ A: less than 10 nM Percent inhibition Example No. B: 10-200nM (0.1 μM) 102 A 103 103 A 99 104 A 99 106 A 100 107 A 104 108 A 103109 A 99 111 A 97 113 A 99 114 A 102 116 A 99 119 A 100 120 A 100 123 A99 124 A 97 163 A 101 164 A 101 178 A 92 179 A 96 180 A 96 186 A 100 189A 100 190 A 100 192 A 101

Test Example 2

Animals

Male ICR mice were supplied by CLEA Japan, Inc (Japan). After arrival tothe vivarium, animals were allowed a minimum of 1 week for acclimation.They were housed under a 12:12-h light/dark cycle in a temperature- andhumidity-controlled laboratory and allowed food and water ad libitum.The care and use of the animals and the experimental protocols used inthis research were approved by the Experimental Animal Care and UseCommittee of Takeda Pharmaceutical Company, Ltd (Osaka, Japan).

Drug Administration

The compounds were suspended in 0.5% methylcellulose in saline ordistilled water, and administered by intraperitoneally (i.p.) or orally(p.o.), respectively. Methamphetamine (Dainippon Sumitomo Pharma Co.,Ltd.) and MK-801 (Sigma-Aldrich, St Louis, Mo.) were dissolved insaline, and administered subcutaneously (s.c.). All drugs were dosed ina volume of 20 mL/kg body weight for mice.

Measurement of Striatal Tissue Cyclic Nucleotides

Male ICR mice were sacrificed by focused microwave irradiation of thebrain at 30 min after administration of the compound. Striatum wereisolated and homogenized in 0.5 N HCl followed by centrifugation.Supernatant concentrations of cyclic nucleotides were measured usingenzyme immunoassay kits (Cayman Chemical, Ann Arbor, Mich.). All datawere represented as means plus the standard errors of the means (n=5-7)and analyzed using a williams' test with significance set at #P<0.025.

Inhibition of Methamphetamine (MAP)- or MK-801-Induced Hyperlocomotion

The widely used animal models of psychosis have been the measurement ofthe extent of hyperlocomotion induced by psychostimulants (e.g.,amphetamine, cocaine, methamphetamine, MK-801 and phencyclidine) inrodents (Psychopharmacology 1999, vol. 145: 237-250). The compounds weretested for its ability to antagonize either MAP- or MK-801-inducedhyperlocomotion in mice. Male ICR mice were habituated in the locomotorchambers with infrared sensors (BrainScienceIdea Co., Ltd. Japan) to theexperiment. After the habituation, animals were treated with eithervehicle or the compounds (3-100 mg/kg, i.p. or 1 mg/kg, p.o.), andMK-801 (0.3 mg/kg, s.c.) or MAP (2 mg/kg, s.c.) was administrated 30 or60 min after i.p. or p.o., respectively. Locomotion activities weremeasured, and accumulated counts (30 or 60 min before and 90 min afteradministration of stimulants) were calculated in each treatment group.All data were represented as means plus the standard errors of the means(n=5-8) and analyzed using a williams' test with significance set at#P<0.025 or Dunnett's t-test with significance set at *P<0.025.

Improvement of MK-801-Induced Prepulse Inhibition (PPI) Deficits.

PPI is a measure of sensorimotor gating and is one of a fewneuropsychological measures in which humans and rodents can be evaluatedin a similar fashion (Psychopharmacology (Berl) 2001, vol. 156:117-154). We evaluated whether compound could reverse PPI deficitsinduced by MK-801 using male ICR mice. Compounds and MK-801 (0.3 mg/kg,s.c.) were administered 30 min and 20 min, respectively, before testing.Experiments employed eight SR-LAB acoustic startle chambers (San DiegoInstruments, San Diego, Calif.), each consisting of a clear, Plexiglascylinder mounted on a platform and housed in ventilated,sound-attenuating external chambers. Placement of mice inside thecylinders allowed the whole-body startle responses induced by theacoustic stimuli to be measured via the transduction of movement intoanalog signals by a piezoelectric unit attached to the platform. Aloudspeaker inside each chamber provided continuous background noise andthe various acoustic stimuli. Test sessions consisted of placement ofindividual animals into the startle chambers and initiation of thebackground noise (70 dB). After a 5-min acclimation period, each subjectwas presented with 54 trials with variable inter-trial intervals (7-23sec). The trials consisted of the following three types: 1) a pulse onlytrial of 118 dB presented for 40 ms during which time the startleresponse was recorded for 40 ms beginning with the onset of the 118 dB,2) two prepulse trial types consisting of a 118 dB presented for 40 mswhich was preceded 100 ms earlier by a 20 ms burst of 76 or 82 dB duringwhich the startle response was recorded for 40 ms beginning with theonset of the 118 dB, and 3) a no stimulus trial in which only backgroundnoise was present. Percent of PPI was calculated separately for each ofthe 2 prepulse dB levels using the following traditional formula:[((average maximum startle on pulse only trials−average maximum startleon prepulse trials)/average maximum startle on pulse only trials)×100].All data were represented as means plus the standard errors of the means(n=8-11) and dose-dependency was analyzed using a williams' test withsignificance set at #P<0.025. *P<0.05, Student's t-test as compared tocontrol group. $P<0.05, Student's t-test as compared to MK-801-treatedgroup. Results are shown in FIG. 1 to FIG. 4.

The graphs of FIG. 1. shows dose-dependent elevation of cAMP (FIG. 1A)and cGMP (FIG. 1B) contents in the mouse striatum by compound A. Thirtymin after administration of the compound A, striatum was isolated frommice and then cAMP and cGMP contents were measured using EIA kits.

The graphs of FIG. 2. shows dose-dependent inhibition of methamphetamine(MAP)- or MK-801-induced hyperlocomotion by compound A. The compound Adecreased spontaneous locomotion (−30-0 min). By administered 30 minbefore MAP (FIG. 2A) or MK-801 (FIG. 2B) treatment, compound A produceda dose-dependent inhibition of stimulant-induced hyperlocomotion (0-90min).

The graph of FIG. 3. shows reversal of MK-801-induced PPI deficits at 82dB prepulse by compound A. By intraperitoneally administered 30 minbefore testing, compounds produced a dose-dependent reversal ofMK-801-induced PPI deficits. Risperidone (RIS, 0.3 mg/kg) alsosignificantly reversed MK-801-induced PPI deficits.

The graph of FIG. 4. shows inhibition of MK-801-induced hyperlocomotionby compounds in mice. By orally administered 60 min before MK-801 (0.3mg/kg, s.c.) treatment, compounds produced significant inhibition ofstimulant-induced hyperlocomotion (0-90 min).

Compounds in figures (FIG. 1 to FIG. 4) correspond to the followingexample.

Compound A (Example 10)

Compound B (Example 104)

Compound C (Example 108)

Compound D (Example 120)

Compound E (Example 163)

Compound F (Example 164)

Compound G (Example 180)

Compound H (Example 192)

Formulation Example 1

(1) Compound of the Example 1 10.0 g (2) Lactose 70.0 g (3) Cornstarch50.0 g (4) Soluble starch  7.0 g (5) Magnesium stearate  3.0 g

After 10.0 g of the compound in Embodiment 1 and 3.0 g of magnesiumstearate were granulated in 70 ml aqueous solution of soluble starch(7.0 g as soluble starch) and then dried, the resulting mixture wasmixed with 70.0 g of lactose and 50.0 g of cornstarch (lactose,cornstarch, soluble starch and magnesium stearate were all products incompliance with Japanese Pharmacopoeia 14^(th) Edition). The mixture wascompressed to obtain a tablet.

INDUSTRIAL APPLICABILITY

The medicine of the present invention can be used as a medicine forpreventing and treating psychiatric disorders such as schizophrenia.

CITATION LIST Patent Literature

Patent Literature 1

WO2006072828

Patent Literature 2

WO2008001182

What is claimed is:
 1. A compound of formula (I):

wherein R¹ represents a substituent, R² represents a hydrogen atom, or asubstituent, R³ represents a hydrogen atom, or a substituent, Ring Arepresents an aromatic ring which can be substituted, and Ring Brepresents a 5-membered heteroaromatic ring which can be substituted;provided that the following compounds:1-(2-chlorophenyl)-6-methyl-3-{5-thioxo-4-[3-(trifluoromethyl)phenyl]-4,5-dihydro-1H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,1-(4-chlorophenyl)-3-[4-(2-fluorophenyl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl]-6-methylpyridazin-4(1H)-one,1-(4-chlorophenyl)-6-methyl-3-{5-thioxo-4-[3-(trifluoromethyl)phenyl]-4,5-dihydro-1H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,1-(4-chlorophenyl)-3-[4-(2-fluorophenyl)-5-(methylsulfanyl)-4H-1,2,4-triazol-3-yl]-6-methylpyridazin-4(1H)-one,1-(4-chlorophenyl)-6-methyl-3-{5-(methylsulfanyl)-4-[3-(trifluoromethyl)phenyl]-4H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,1-(2-chlorophenyl)-6-methyl-3-{5-(methylsulfanyl)-4-[3-(trifluoromethyl)phenyl]-4H-1,2,4-triazol-3-yl}pyridazin-4(1H)-one,3-(3,5-dimethyl-1H-pyrazol-1-yl)-1-phenylpyridazin-4(1H)-one,1-(4-chlorophenyl)-3-{1-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]-1H-pyrazol-5-yl}pyridazin-4(1H)-one,3-[1-(2-fluorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(3-chiorophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(4-methoxyphenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-(1-phenyl-1H-pyrazol-5-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(3-nitrophenyl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(1,1-dioxidotetrahydrothiophen-3-yl)-1H-pyrazol-5-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(4-methylphenyl)-1H-pyrazol-5-yl]-1-phenylpyridazin-4(1H)-one,3-[1-(4-chlorophenyl)-1H-pyrazol-5-yl]-1-phenylpyridazin-4(1H)-one,3-(4-ethyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-1-(4-methylphenyl)pyridazin-4(1H)-one,1-(4-chlorophenyl)-3-{1-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]-1H-pyrazol-3-yl}pyridazin-4(1H)-one,3-[1-(2-fluorophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(3-chlorophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(3-methoxyphenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-(1-phenyl-1H-pyrazol-3-yl)-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(3-nitrophenyl)-1H-pyrazol-3-yl]-1-[3-(trifluoromethyl)phenyl]pyridazin-4(1H)-one,3-[1-(4-methylphenyl)-1H-pyrazol-3-yl]-1-phenylpyridazin-4(1H)-one,3-[1-(4-chlorophenyl)-1H-pyrazol-3-yl]-1-phenylpyridazin-4(1H)-one, acompound of formula:

wherein Ring A′ is a benzene ring which can be substituted by onesubstituent selected from a halogen atom, and an alkyl group, R^(1′) is(1) an ethyl group, or (2) a phenyl group which can be substituted byone or more substituents selected from a fluorine atom, and atrifluoromethyl group, R^(3′) is a hydrogen atom, or a methyl group, andRa is a hydrogen atom, or a C₁₋₄ acyclic hydrocarbon group which can besubstituted, a compound of formula:

wherein Ring A″ is a benzene ring which can be substituted by halogen,and R^(1″) is an acyl group are excluded; or a salt thereof.
 2. Thecompound according to claim 1, wherein R² represents a halogen atom, ahydroxy group, a C₁₋₁₀ alkyl group which can be substituted, or a C₁₋₁₀alkoxy group which can be substituted.
 3. The compound according toclaim 2, wherein R² represents a C₁₋₁₀ alkoxy group which can besubstituted by one or more substituents selected from a halogen atom, aC₁₋₁₀ alkoxy group, and a C₃₋₇ cycloalkyl group.
 4. The compoundaccording to claim 2, wherein R² represents a C₁₋₁₀ alkoxy group.
 5. Thecompound according to claim 2, wherein R¹ represents a phenyl groupwhich can be substituted by 1 to 5 substituents selected from a halogenatom, a C₁₋₁₀ alkyl group which can be substituted, and a C₁₋₁₀ alkoxygroup which can be substituted.
 6. The compound according to claim 2,wherein R¹ represents a phenyl group which can be substituted by 1 to 5substituents selected from a halogen atom, a C₁₋₁₀ alkyl group, and aC₁₋₁₀ alkoxy group.
 7. The compound according to claim 2, wherein R¹represents a phenyl group which can be substituted by 1 to 5 halogenatoms.
 8. The compound according to claim 2, wherein R³ represents ahydrogen atom, or a C₁₋₁₀ alkoxy group which can be substituted.
 9. Thecompound according to claim 2, wherein R³ represents a hydrogen atom, ora C₁₋₁₀ alkoxy group.
 10. The compound according to claim 2, wherein R³represents a hydrogen atom.
 11. The compound according to claim 2,wherein Ring A represents a benzene ring which can be substituted by 1to 5 substituents selected from (1) a halogen atom, (2) a C₁₋₁₀ alkylgroup which can be substituted, (3) a C₁₋₁₀ alkoxy group which can besubstituted, (4) a 4- to 6-membered heterocyclic group containing 0 or 1oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms which can besubstituted, (5) a C₁₋₁₀ alkylsulfonyl group which can be substituted,(6) a C₃₋₇ cycloalkyl group which can be substituted, (7) a cyano group,(8) a carbamoyl group which can be substituted, (9) a C₁₋₁₀alkylsulfonyloxy group which can be substituted, (10) a C₃₋₇cycloalkyl-C₂₋₆ alkynyl group which can be substituted, (11) atetrahydropyranyl group which can be substituted, (12) a dihydropyranylgroup which can be substituted, (13) a mono-(C₁₋₁₀ alkyl-carbonyl)-aminogroup which can be substituted, (14) a C₁₋₁₀ alkoxy-carbonyl group whichcan be substituted, (15) a C₁₋₁₀ alkylsulfinyl group which can besubstituted, and (16) a C₁₋₁₀ alkylsulfanyl group which can besubstituted.
 12. The compound according to claim 2, wherein Ring Arepresents a benzene ring which can be substituted by 1 to 5substituents selected from (1) a halogen atom, (2) a C₁₋₁₀ alkyl groupwhich can be substituted, (3) a C₁₋₁₀ alkoxy group which can besubstituted, (4) a C₃₋₇ cycloalkyl group, (5) a halogeno C₁₋₁₀alkylsulfonyloxy group, (6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by oneor more substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted, and a C₁₋₁₀ alkyl group which can be substituted. 13.The compound according to claim 2, wherein Ring A represents a benzenering which can be substituted by 1 to 5 substituents selected from (1) ahalogen atom, (2) a C₁₋₁₀ alkyl group which can be substituted by 1 to 3halogen atoms, (3) a C₁₋₁₀ alkoxy group which can be substituted by 1 to3 halogen atoms, (4) a C₃₋₇ cycloalkyl group, (5) a halogeno C₁₋₁₀alkylsulfonyloxy group, (6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by 1to 4 substituents selected from a halogen atom, a hydroxy group, an oxogroup, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which can besubstituted by halogen, and a C₁₋₁₀ alkyl group which can be substitutedby halogen.
 14. The compound according to claim 2, wherein Ring Arepresents a benzene ring which is substituted with (1) (i) 1 or 2halogen atoms, or (ii) one C₁₋₁₀ alkoxy group, and (2) one 4- to6-membered heterocyclic group containing 0 or 1 oxygen atom, and 1 to 3nitrogen atoms as heteroatoms which can be substituted by 1 to 4substituents selected from a halogen atom, a hydroxy group, an oxogroup, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ to alkoxy group which canbe substituted by halogen, and a C₁₋₁₀ alkyl group which can besubstituted by halogen.
 15. The compound according to claim 14, whereinthe 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms represents a morpholino group,a pyrrolyl group, a dihydropyrrolyl group, a pyrazolyl group, adihydropyrazolyl group, a piperidyl group, an azetidinyl group, apyrrolidinyl group, an oxazolidinyl group, an imidazolyl group or animidazolidinyl group.
 16. The compound according to claim 2, whereinRing B represents an imidazole ring, a pyrazole ring, a triazole ring ora tetrazole ring, each of which can be further substituted with 1 to 3substituents selected from a halogen atom, and a C₁₋₁₀ alkyl group whichcan be substituted by halogen.
 17. The compound according to claim 2,wherein Ring B represents a pyrazole ring which can be furthersubstituted with 1 to 3 substituents selected from a halogen atom, and aC₁₋₁₀ alkyl group which can be substituted by halogen.
 18. The compoundaccording to claim 2, wherein Ring B represents a pyrazole ring.
 19. Thecompound according to claim 2, wherein R¹ represents a phenyl groupwhich can be substituted by 1 to 5 substituents selected from a halogenatom, a C₁₋₁₀ alkyl group which can be substituted, and a C₁₋₁₀ alkoxygroup which can be substituted, R² represents a halogen atom, a hydroxygroup, a C₁₋₁₀ alkyl group which can be substituted, or a C₁₋₁₀ alkoxygroup which can be substituted, R³ represents a hydrogen atom, or aC₁₋₁₀ alkoxy group which can be substituted, Ring A represents a benzenering which can be substituted by 1 to 5 substituents selected from (1) ahalogen atom, (2) a C₁₋₁₀ alkyl group which can be substituted, (3) aC₁₋₁₀ alkoxy group which can be substituted, (4) a 4- to 6-memberedheterocyclic group containing 0 or 1 oxygen atom, and 1 to 3 nitrogenatoms as heteroatoms which can be substituted, (5) a C₁₋₁₀ alkylsulfonylgroup which can be substituted, (6) a C₃₋₇ cycloalkyl group which can besubstituted, (7) a cyano group, (8) a carbamoyl group which can besubstituted, (9) a C₁₋₁₀ alkylsulfonyloxy group which can besubstituted, (10) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group which can besubstituted, (11) a tetrahydropyranyl group which can be substituted,(12) a dihydropyranyl group which can be substituted, (13) a mono-(C₁₋₁₀alkyl-carbonyl)-amino group which can be substituted, (14) a C₁₋₁₀alkoxy-carbonyl group which can be substituted, (15) a C₁₋₁₀alkylsulfinyl group which can be substituted, and (16) a C₁₋₁₀alkylsulfanyl group which can be substituted, and Ring B represents animidazole ring, a pyrazole ring, a triazole ring or a tetrazole ring,each of which can be further substituted with 1 to 3 substituentsselected from a halogen atom, and a C₁₋₁₀ alkyl group which can besubstituted by halogen.
 20. The compound according to claim 19, wherein.Ring A represents a benzene ring which can be substituted by 1 to 5substituents selected from (1) a halogen atom, (2) a C₁₋₁₀ alkyl groupwhich can be substituted, (3) a C₁₋₁₀ alkoxy group which can besubstituted, (4) a C₃₋₇ cycloalkyl group, (5) a halogeno C₁₋₁₀alkylsulfonyloxy group, (6) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and(7) a 4- to 6-membered heterocyclic group containing 0 or 1 oxygen atom,and 1 to 3 nitrogen atoms as heteroatoms which can be substituted by oneor more substituents selected from a halogen atom, a hydroxy group, anoxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which canbe substituted, and a C₁₋₁₀ alkyl group which can be substituted. 21.The compound according to claim 2, wherein R¹ represents a phenyl groupwhich can be substituted by 1 to 5 substituents selected from a halogenatom, a C₁₋₁₀ alkyl group, and a C₁₋₁₀ alkoxy group, R² represents aC₁₋₁₀ alkoxy group which can be substituted by one or more substituentsselected from a halogen atom, a C₁₋₁₀ alkoxy group, and a C₃₋₇cycloalkyl group, R³ represents a hydrogen atom, or a C₁₋₁₀ alkoxygroup, Ring A represents a benzene ring which can be substituted by 1 to5 substituents selected from (1) a halogen atom, (2) a C₁₋₁₀ alkyl groupwhich can be substituted by 1 to 3 halogen atoms, (3) a C₁₋₁₀ alkoxygroup which can be substituted by 1 to 3 halogen atoms, (4) a C₃₋₇cycloalkyl group, (5) a halogeno C₁₋₁₀ alkylsulfonyloxy group, (6) aC₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, and (7) a 4- to 6-memberedheterocyclic group containing 0 or 1 oxygen atom, and 1 to 3 nitrogenatoms as heteroatoms which can be substituted by 1 to 4 substituentsselected from a halogen atom, a hydroxy group, an oxo group, a C₁₋₁₀alkoxy-carbonyl group, a C₁₋₁₀ alkoxy group which can be substituted byhalogen, and a C₁₋₁₀ alkyl group which can be substituted by halogen,Ring B represents a pyrazole ring which can be further substituted with1 to 3 substituents selected from a halogen atom, and a C₁₋₁₀ alkylgroup which can be substituted by halogen.
 22. The compound according toclaim 2, wherein R¹ represents a phenyl group which can be substitutedby 1 to 5 halogen atoms, R² represents a C₁₋₁₀ alkoxy group, R³represents a hydrogen atom, Ring A represents a benzene ring which issubstituted with (1) (i) 1 or 2 halogen atoms, or (ii) one C₁₋₁₀ alkoxygroup, and (2) one 4- to 6-membered heterocyclic group containing 0 or 1oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms which can besubstituted by 1 to 4 substituents selected from a halogen atom, ahydroxy group, an oxo group, a C₁₋₁₀ alkoxy-carbonyl group, a C₁₋₁₀alkoxy group which can be substituted by halogen, and a C₁₋₁₀ alkylgroup which can be substituted by halogen, Ring B represents a pyrazolering.
 23. The compound according to claim 22, wherein the 4- to6-membered heterocyclic group containing 0 or 1 oxygen atom, and 1 to 3nitrogen atoms as heteroatoms represents a morpholino group, a pyrrolylgroup, a dihydropyrrolyl group, a pyrazolyl group, a dihydropyrazolylgroup, a piperidyl group, an azetidinyl group, a pyrrolidinyl group, anoxazolidinyl group, an imidazolyl group or an imidazolidinyl group. 24.The compound according to claim 1, wherein R¹ represents an aromaticgroup which can be substituted, Ring A represents an aromatic ring whichis substituted with (a) one substituent selected from (1) a C₃₋₇cycloalkyl group which can be substituted, and (2) a 4- to 6-memberedheterocyclic group containing 1 to 5 heteroatoms selected from anitrogen atom, a sulfur atom, and an oxygen atom which can besubstituted, and (b) one or more further substituents.
 25. The compoundaccording to claim 24, wherein R¹ represents a phenyl group which can besubstituted, R² represents a hydrogen atom, a halogen atom, a hydroxygroup, a C₁₋₁₀ alkyl group which can be substituted, or a C₁₋₁₀ alkoxygroup which can be substituted, R³ represents a hydrogen atom, or aC₁₋₁₀ alkoxy group which can be substituted, Ring A represents a benzenering which is substituted with one substituent selected from (1) a C₃₋₇cycloalkyl group which can be substituted, (2) a dihydropyranyl groupwhich can be substituted, (3) a tetrahydropyranyl group which can besubstituted, and (4) a 4- to 6-membered heterocyclic group containing 0or 1 oxygen atom, and 1 to 3 nitrogen atoms as heteroatoms which can besubstituted, and can be substituted by further substituents, and Ring Brepresents an imidazole ring, a pyrazole ring, a triazole ring, atetrazole ring, an isoxazole ring, an 1,3-oxazole ring, a furan ring, ora thiophene ring, each of which can be substituted.
 26. The compoundaccording to claim 25, wherein the 4- to 6-membered heterocyclic groupcontaining 0 or 1 oxygen atom, and 1 to 3 nitrogen atoms as heteroatomsrepresents a morpholino group, a pyrrolyl group, a dihydropyrrolylgroup, a pyrazolyl group, a dihydropyrazolyl group, a piperidyl group,an azetidinyl group, a pyrrolidinyl group, an oxazolidinyl group, animidazolyl group, an imidazolidinyl group, an isoxazolyl group, apyridyl group, a piperazinyl group, or a thiazolyl group.
 27. Thecompound according to claim 24, wherein the further substituents are 1to 4 substituents selected from (1) a halogen atom, (2) an oxo group,(3) a hydroxy group, (4) a C₁₋₁₀ alkyl group which can be substituted,(5) a C₁₋₁₀ alkoxy group which can be substituted, (6) a C₁₋₁₀alkylsulfonyl group, (7) a morpholin-4-yl sulfonyl group, (8) a cyanogroup, (9) a carbamoyl group, (10) a halogeno C₁₋₁₀ alkylsulfonyloxygroup, (11) a C₃₋₇ cycloalkyl-C₂₋₆ alkynyl group, (12) a di-C₁₋₁₀alkyl-amino group, (13) a mono-(C₁₋₁₀ alkyl-carbonyl)-amino group, (14)a C₁₋₁₀ alkoxy-carbonyl group, (15) a phenoxy group, (16) a C₁₋₁₀alkylsulfinyl group, (17) a di-C₁₋₁₀ alkyl-amino group, (18) abenzimidazole-2-yloxy group, and (19) a benzimidazole-2-yl sulfonylgroup.
 28. The compound according to claim 24, wherein R¹ represents aphenyl group which can be substituted by 1 to 5 halogen atoms, R²represents a hydrogen atom or a C₁₋₁₀ alkoxy group, R³ represents ahydrogen atom, Ring A represents a benzene ring, which is substitutedwith one 4- to 6-membered heterocyclic group containing 0 or 1 oxygenatom, and 1 to 3 nitrogen atoms as heteroatoms which can be substitutedby 1 to 4 substituents selected from a halogen atom, a hydroxy group, anoxo group, halogeno C₁₋₁₀ alkoxy group, a C₁₋₁₀ alkoxy-carbonyl, and aC₁₋₁₀ alkyl group which can be substituted by halogen, and which can befurther substituted with 1 or 2 substituents selected from a halogenatom and a C₁₋₁₀ alkoxy group, and Ring B represents a pyrazole ring.29. The compound according to claim 28, wherein the 4- to 6-memberedheterocyclic group containing 0 or 1 oxygen atom, and 1 to 3 nitrogenatoms as heteroatoms represents a morpholino group, a pyrrolyl group, adihydropyrrolyl group, a pyrazolyl group, a dihydropyrazolyl group, apiperidyl group, an azetidinyl group, a pyrrolidinyl group, anoxazolidinyl group, an imidazolyl group or an imidazolidinyl group. 30.1-[2-fluoro-4-(3,3,4,4-tetrafluoropyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof. 31.1-[2-fluoro-4-(2-oxopyrrolidin-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof. 32.1-[4-(3,4-difluoro-1H-pyrrol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof. 33.1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof. 34.1-[4-(4-chloro-1H-pyrazol-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof. 35.1-[2-fluoro-4-(2-oxo-1,3-oxazolidin-3-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof 36.3-[1-(2-fluorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one,or a salt thereof. 37.3-[1-(3-chlorophenyl)-1H-pyrazol-5-yl]-1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxypyridazin-4(1H)-one,or a salt thereof. 38.1-[4-(4,4-dimethyl-2-oxopyrrolidin-1-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(IH)-one, or a salt thereof. 39.1-[4-(5,5-dimethyl-2-oxo-1,3-oxazolidin-3-yl)-2-fluorophenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof. 40.5-methoxy-1-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-3-(1-phenyl-1H-pyrazol-5-yl)pyridazin-4(1H)-one,or a salt thereof.
 41. A prodrug of the compound according to claim
 142. A medicament comprising the compound according to claim 1 or aprodrug thereof.
 43. A medicament comprising a compound of formula (I₀):

wherein R¹ represents a substituent, R² represents a hydrogen atom, or asubstituent, R³ represents a hydrogen atom, or a substituent, Ring Arepresents an aromatic ring which can be substituted, and Ring Brepresents a 5-membered heteroaromatic ring which can be substituted, ora salt thereof, or a prodrug thereof.
 44. The medicament according toclaim 43 which is an agent for inhibiting phosphodiesterase 10A.
 45. Themedicament according to claim 43 which is for preventing or treatingschizophrenia
 46. A method of preventing or treating schizophreniacomprising administrating an effective amount of a compound of formula(I₀):

wherein R¹ represents a substituent, R² represents a hydrogen atom, or asubstituent, R³ represents a hydrogen atom, or a substituent, Ring Arepresents an aromatic ring which can be substituted, and Ring Brepresents a 5-membered heteroaromatic ring which can be substituted, ora salt thereof, or a prodrug thereof to a mammal.
 47. Use of a compoundof formula (I₀):

wherein R¹ represents a substituent, R² represents a hydrogen atom, or asubstituent, R³ represents a hydrogen atom, or a substituent, Ring Arepresents an aromatic ring which can be substituted, and Ring Brepresents a 5-membered heteroaromatic ring which can be substituted, ora salt thereof, or a prodrug thereof as a medicament.
 48. Use of acompound of formula (I₀):

wherein R¹ represents a substituent, R² represents a hydrogen atom, or asubstituent, R³ represents a hydrogen atom, or a substituent, Ring Arepresents an aromatic ring which can be substituted, and Ring Brepresents a 5-membered heteroaromatic ring which can be substituted, ora salt thereof, or a prodrug thereof in the manufacture of a medicamentfor preventing or treating schizophrenia.